diff --git a/modules/categoryTranslation.js b/modules/categoryTranslation.js
index 57267095ff0..ba73aa01b85 100644
--- a/modules/categoryTranslation.js
+++ b/modules/categoryTranslation.js
@@ -34,13 +34,13 @@ export const registerAdserver = hook('async', function(adServer) {
 }, 'registerAdserver');
 registerAdserver();
 
-export const getAdserverCategoryHook = timedBidResponseHook('categoryTranslation', function getAdserverCategoryHook(fn, adUnitCode, bid) {
+export const getAdserverCategoryHook = timedBidResponseHook('categoryTranslation', function getAdserverCategoryHook(fn, adUnitCode, bid, reject) {
   if (!bid) {
-    return fn.call(this, adUnitCode); // if no bid, call original and let it display warnings
+    return fn.call(this, adUnitCode, bid, reject); // if no bid, call original and let it display warnings
   }
 
   if (!config.getConfig('adpod.brandCategoryExclusion')) {
-    return fn.call(this, adUnitCode, bid);
+    return fn.call(this, adUnitCode, bid, reject);
   }
 
   let localStorageKey = (config.getConfig('brandCategoryTranslation.translationFile')) ? DEFAULT_IAB_TO_FW_MAPPING_KEY_PUB : DEFAULT_IAB_TO_FW_MAPPING_KEY;
@@ -63,7 +63,7 @@ export const getAdserverCategoryHook = timedBidResponseHook('categoryTranslation
       logError('Translation mapping data not found in local storage');
     }
   }
-  fn.call(this, adUnitCode, bid);
+  fn.call(this, adUnitCode, bid, reject);
 });
 
 export function initTranslation(url, localStorageKey) {
diff --git a/modules/currency.js b/modules/currency.js
index f0ad6681afa..2c8070bcb08 100644
--- a/modules/currency.js
+++ b/modules/currency.js
@@ -1,10 +1,9 @@
-import { logInfo, logWarn, logError, logMessage } from '../src/utils.js';
-import { getGlobal } from '../src/prebidGlobal.js';
-import { createBid } from '../src/bidfactory.js';
+import {logError, logInfo, logMessage, logWarn} from '../src/utils.js';
+import {getGlobal} from '../src/prebidGlobal.js';
 import CONSTANTS from '../src/constants.json';
-import { ajax } from '../src/ajax.js';
-import { config } from '../src/config.js';
-import { getHook } from '../src/hook.js';
+import {ajax} from '../src/ajax.js';
+import {config} from '../src/config.js';
+import {getHook} from '../src/hook.js';
 import {defer} from '../src/utils/promise.js';
 import {timedBidResponseHook} from '../src/utils/perfMetrics.js';
 
@@ -181,9 +180,9 @@ function resetCurrency() {
   bidderCurrencyDefault = {};
 }
 
-export const addBidResponseHook = timedBidResponseHook('currency', function addBidResponseHook(fn, adUnitCode, bid) {
+export const addBidResponseHook = timedBidResponseHook('currency', function addBidResponseHook(fn, adUnitCode, bid, reject) {
   if (!bid) {
-    return fn.call(this, adUnitCode); // if no bid, call original and let it display warnings
+    return fn.call(this, adUnitCode, bid, reject); // if no bid, call original and let it display warnings
   }
 
   let bidder = bid.bidderCode || bid.bidder;
@@ -209,10 +208,10 @@ export const addBidResponseHook = timedBidResponseHook('currency', function addB
 
   // execute immediately if the bid is already in the desired currency
   if (bid.currency === adServerCurrency) {
-    return fn.call(this, adUnitCode, bid);
+    return fn.call(this, adUnitCode, bid, reject);
   }
 
-  bidResponseQueue.push(wrapFunction(fn, this, [adUnitCode, bid]));
+  bidResponseQueue.push(wrapFunction(fn, this, [adUnitCode, bid, reject]));
   if (!currencySupportEnabled || currencyRatesLoaded) {
     processBidResponseQueue();
   } else {
@@ -239,7 +238,8 @@ function wrapFunction(fn, context, params) {
         }
       } catch (e) {
         logWarn('Returning NO_BID, getCurrencyConversion threw error: ', e);
-        params[1] = createBid(CONSTANTS.STATUS.NO_BID, bid.getIdentifiers());
+        // TODO: in v8, this should not continue with a "NO_BID"
+        params[1] = params[2](CONSTANTS.REJECTION_REASON.CANNOT_CONVERT_CURRENCY);
       }
     }
     return fn.apply(context, params);
diff --git a/modules/dchain.js b/modules/dchain.js
index 79e20520e93..daf97a7551f 100644
--- a/modules/dchain.js
+++ b/modules/dchain.js
@@ -109,7 +109,7 @@ function isValidDchain(bid) {
   }
 }
 
-export const addBidResponseHook = timedBidResponseHook('dchain', function addBidResponseHook(fn, adUnitCode, bid) {
+export const addBidResponseHook = timedBidResponseHook('dchain', function addBidResponseHook(fn, adUnitCode, bid, reject) {
   const basicDchain = {
     ver: '1.0',
     complete: 0,
@@ -140,7 +140,7 @@ export const addBidResponseHook = timedBidResponseHook('dchain', function addBid
     bid.meta.dchain = basicDchain;
   }
 
-  fn(adUnitCode, bid);
+  fn(adUnitCode, bid, reject);
 });
 
 export function init() {
diff --git a/modules/debugging/legacy.js b/modules/debugging/legacy.js
index 15b05cded64..e83b99c5194 100644
--- a/modules/debugging/legacy.js
+++ b/modules/debugging/legacy.js
@@ -54,7 +54,7 @@ export function applyBidOverrides(overrideObj, bidObj, bidType, logger) {
   }, bidObj);
 }
 
-export function addBidResponseHook(next, adUnitCode, bid) {
+export function addBidResponseHook(next, adUnitCode, bid, reject) {
   const {overrides, logger} = this;
 
   if (bidderExcluded(overrides.bidders, bid.bidderCode)) {
@@ -70,7 +70,7 @@ export function addBidResponseHook(next, adUnitCode, bid) {
     });
   }
 
-  next(adUnitCode, bid);
+  next(adUnitCode, bid, reject);
 }
 
 export function addBidderRequestsHook(next, bidderRequests) {
diff --git a/modules/mass.js b/modules/mass.js
index 6a01f06bd90..113fdce8d4f 100644
--- a/modules/mass.js
+++ b/modules/mass.js
@@ -78,7 +78,7 @@ export function updateRenderers() {
 /**
  * Before hook for 'addBidResponse'.
  */
-export const addBidResponseHook = timedBidResponseHook('mass', function addBidResponseHook(next, adUnitCode, bid, {index = auctionManager.index} = {}) {
+export const addBidResponseHook = timedBidResponseHook('mass', function addBidResponseHook(next, adUnitCode, bid, reject, {index = auctionManager.index} = {}) {
   let renderer;
   for (let i = 0; i < renderers.length; i++) {
     if (renderers[i].match(bid)) {
@@ -104,7 +104,7 @@ export const addBidResponseHook = timedBidResponseHook('mass', function addBidRe
     addListenerOnce();
   }
 
-  next(adUnitCode, bid);
+  next(adUnitCode, bid, reject);
 });
 
 /**
diff --git a/modules/multibid/index.js b/modules/multibid/index.js
index fb28be83fa8..76f4ede8f8e 100644
--- a/modules/multibid/index.js
+++ b/modules/multibid/index.js
@@ -99,7 +99,7 @@ export function adjustBidderRequestsHook(fn, bidderRequests) {
    * @param {String} ad unit code for bid
    * @param {Object} bid object
 */
-export const addBidResponseHook = timedBidResponseHook('multibid', function addBidResponseHook(fn, adUnitCode, bid) {
+export const addBidResponseHook = timedBidResponseHook('multibid', function addBidResponseHook(fn, adUnitCode, bid, reject) {
   let floor = deepAccess(bid, 'floorData.floorValue');
 
   if (!config.getConfig('multibid')) resetMultiConfig();
@@ -107,7 +107,7 @@ export const addBidResponseHook = timedBidResponseHook('multibid', function addB
   // Else checks if multiconfig exists and bid bidderCode exists within config
   // Else continue with no modifications
   if (hasMultibid && multiConfig[bid.bidderCode] && deepAccess(bid, 'video.context') === 'adpod') {
-    fn.call(this, adUnitCode, bid);
+    fn.call(this, adUnitCode, bid, reject);
   } else if (hasMultibid && multiConfig[bid.bidderCode]) {
     // Set property multibidPrefix on bid
     if (multiConfig[bid.bidderCode].prefix) bid.multibidPrefix = multiConfig[bid.bidderCode].prefix;
@@ -127,7 +127,7 @@ export const addBidResponseHook = timedBidResponseHook('multibid', function addB
         if (multiConfig[bid.bidderCode].prefix) bid.targetingBidder = multiConfig[bid.bidderCode].prefix + length;
         if (length === multiConfig[bid.bidderCode].maxbids) multibidUnits[adUnitCode][bid.bidderCode].maxReached = true;
 
-        fn.call(this, adUnitCode, bid);
+        fn.call(this, adUnitCode, bid, reject);
       } else {
         logWarn(`Filtering multibid received from bidder ${bid.bidderCode}: ` + ((multibidUnits[adUnitCode][bid.bidderCode].maxReached) ? `Maximum bid limit reached for ad unit code ${adUnitCode}` : 'Bid cpm under floors value.'));
       }
@@ -137,10 +137,10 @@ export const addBidResponseHook = timedBidResponseHook('multibid', function addB
       deepSetValue(multibidUnits, [adUnitCode, bid.bidderCode], {ads: [bid]});
       if (multibidUnits[adUnitCode][bid.bidderCode].ads.length === multiConfig[bid.bidderCode].maxbids) multibidUnits[adUnitCode][bid.bidderCode].maxReached = true;
 
-      fn.call(this, adUnitCode, bid);
+      fn.call(this, adUnitCode, bid, reject);
     }
   } else {
-    fn.call(this, adUnitCode, bid);
+    fn.call(this, adUnitCode, bid, reject);
   }
 });
 
diff --git a/modules/prebidServerBidAdapter/index.js b/modules/prebidServerBidAdapter/index.js
index 5bdf9868d24..856b962e8a0 100644
--- a/modules/prebidServerBidAdapter/index.js
+++ b/modules/prebidServerBidAdapter/index.js
@@ -950,10 +950,6 @@ Object.assign(ORTB2.prototype, {
         (seatbid.bid || []).forEach(bid => {
           let bidRequest = this.getBidRequest(bid.impid, seatbid.seat);
           if (bidRequest == null) {
-            if (!s2sConfig.allowUnknownBidderCodes) {
-              logWarn(`PBS adapter received bid from unknown bidder (${seatbid.seat}), but 's2sConfig.allowUnknownBidderCodes' is not set. Ignoring bid.`);
-              return;
-            }
             // for stored impression, a request was made with bidder code `null`. Pick it up here so that NO_BID, BID_WON, etc events
             // can work as expected (otherwise, the original request will always result in NO_BID).
             bidRequest = this.getBidRequest(bid.impid, null);
@@ -968,6 +964,7 @@ Object.assign(ORTB2.prototype, {
             transactionId: this.adUnitsByImp[bid.impid].transactionId,
             auctionId: this.auctionId,
           });
+          bidObject.requestBidder = bidRequest?.bidder;
           bidObject.requestTimestamp = this.requestTimestamp;
           bidObject.cpm = cpm;
           if (bid?.ext?.prebid?.meta?.adaptercode) {
@@ -1158,8 +1155,15 @@ export function PrebidServer() {
         onBid: function ({adUnit, bid}) {
           const metrics = bid.metrics = s2sBidRequest.metrics.fork().renameWith();
           metrics.checkpoint('addBidResponse');
-          if (metrics.measureTime('addBidResponse.validate', () => isValid(adUnit, bid))) {
-            addBidResponse(adUnit, bid);
+          if ((bid.requestId == null || bid.requestBidder == null) && !s2sBidRequest.s2sConfig.allowUnknownBidderCodes) {
+            logWarn(`PBS adapter received bid from unknown bidder (${bid.bidder}), but 's2sConfig.allowUnknownBidderCodes' is not set. Ignoring bid.`);
+            addBidResponse.reject(adUnit, bid, CONSTANTS.REJECTION_REASON.BIDDER_DISALLOWED);
+          } else {
+            if (metrics.measureTime('addBidResponse.validate', () => isValid(adUnit, bid))) {
+              addBidResponse(adUnit, bid);
+            } else {
+              addBidResponse.reject(adUnit, bid, CONSTANTS.REJECTION_REASON.INVALID);
+            }
           }
         }
       })
diff --git a/modules/priceFloors.js b/modules/priceFloors.js
index e4203fd73d3..5aee87d474e 100644
--- a/modules/priceFloors.js
+++ b/modules/priceFloors.js
@@ -20,7 +20,6 @@ import {ajaxBuilder} from '../src/ajax.js';
 import * as events from '../src/events.js';
 import CONSTANTS from '../src/constants.json';
 import {getHook} from '../src/hook.js';
-import {createBid} from '../src/bidfactory.js';
 import {find} from '../src/polyfill.js';
 import {getRefererInfo} from '../src/refererDetection.js';
 import {bidderSettings} from '../src/bidderSettings.js';
@@ -694,11 +693,11 @@ function shouldFloorBid(floorData, floorInfo, bid) {
  * @summary The main driving force of floors. On bidResponse we hook in and intercept bidResponses.
  * And if the rule we find determines a bid should be floored we will do so.
  */
-export const addBidResponseHook = timedBidResponseHook('priceFloors', function addBidResponseHook(fn, adUnitCode, bid) {
+export const addBidResponseHook = timedBidResponseHook('priceFloors', function addBidResponseHook(fn, adUnitCode, bid, reject) {
   let floorData = _floorDataForAuction[bid.auctionId];
   // if no floor data then bail
   if (!floorData || !bid || floorData.skipped) {
-    return fn.call(this, adUnitCode, bid);
+    return fn.call(this, adUnitCode, bid, reject);
   }
 
   const matchingBidRequest = auctionManager.index.getBidRequest(bid);
@@ -708,7 +707,7 @@ export const addBidResponseHook = timedBidResponseHook('priceFloors', function a
 
   if (!floorInfo.matchingFloor) {
     logWarn(`${MODULE_NAME}: unable to determine a matching price floor for bidResponse`, bid);
-    return fn.call(this, adUnitCode, bid);
+    return fn.call(this, adUnitCode, bid, reject);
   }
 
   // determine the base cpm to use based on if the currency matches the floor currency
@@ -724,7 +723,7 @@ export const addBidResponseHook = timedBidResponseHook('priceFloors', function a
       adjustedCpm = getGlobal().convertCurrency(bid.cpm, bidResponseCurrency.toUpperCase(), floorCurrency);
     } catch (err) {
       logError(`${MODULE_NAME}: Unable do get currency conversion for bidResponse to Floor Currency. Do you have Currency module enabled? ${bid}`);
-      return fn.call(this, adUnitCode, bid);
+      return fn.call(this, adUnitCode, bid, reject);
     }
   }
 
@@ -737,25 +736,12 @@ export const addBidResponseHook = timedBidResponseHook('priceFloors', function a
   // now do the compare!
   if (shouldFloorBid(floorData, floorInfo, bid)) {
     // bid fails floor -> throw it out
-    // create basic bid no-bid with necessary data fro analytics adapters
-    let flooredBid = createBid(CONSTANTS.STATUS.NO_BID, bid.getIdentifiers());
-    Object.assign(flooredBid, pick(bid, [
-      'floorData',
-      'width',
-      'height',
-      'mediaType',
-      'currency',
-      'originalCpm',
-      'originalCurrency',
-      'getCpmInNewCurrency',
-    ]));
-    flooredBid.status = CONSTANTS.BID_STATUS.BID_REJECTED;
-    // if floor not met update bid with 0 cpm so it is not included downstream and marked as no-bid
-    flooredBid.cpm = 0;
+    // continue with a "NO_BID" bid, TODO: remove this in v8
+    const flooredBid = reject(CONSTANTS.REJECTION_REASON.FLOOR_NOT_MET);
     logWarn(`${MODULE_NAME}: ${flooredBid.bidderCode}'s Bid Response for ${adUnitCode} was rejected due to floor not met (adjusted cpm: ${bid?.floorData?.cpmAfterAdjustments}, floor: ${floorInfo?.matchingFloor})`, bid);
-    return fn.call(this, adUnitCode, flooredBid);
+    return fn.call(this, adUnitCode, flooredBid, reject);
   }
-  return fn.call(this, adUnitCode, bid);
+  return fn.call(this, adUnitCode, bid, reject);
 });
 
 config.getConfig('floors', config => handleSetFloorsConfig(config.floors));
diff --git a/src/adapters/bidderFactory.js b/src/adapters/bidderFactory.js
index c60f4b8a015..d0b716d656d 100644
--- a/src/adapters/bidderFactory.js
+++ b/src/adapters/bidderFactory.js
@@ -202,6 +202,8 @@ export function newBidder(spec) {
         adUnitCodesHandled[adUnitCode] = true;
         if (metrics.measureTime('addBidResponse.validate', () => isValid(adUnitCode, bid))) {
           addBidResponse(adUnitCode, bid);
+        } else {
+          addBidResponse.reject(adUnitCode, bid, CONSTANTS.REJECTION_REASON.INVALID)
         }
       }
 
@@ -262,6 +264,7 @@ export function newBidder(spec) {
             bid.adapterCode = bidRequest.bidder;
             if (isInvalidAlternateBidder(bid.bidderCode, bidRequest.bidder)) {
               logWarn(`${bid.bidderCode} is not a registered partner or known bidder of ${bidRequest.bidder}, hence continuing without bid. If you wish to support this bidder, please mark allowAlternateBidderCodes as true in bidderSettings.`);
+              addBidResponse.reject(bidRequest.adUnitCode, bid, CONSTANTS.REJECTION_REASON.BIDDER_DISALLOWED)
               return;
             }
             // creating a copy of original values as cpm and currency are modified later
@@ -272,6 +275,7 @@ export function newBidder(spec) {
             addBidWithCode(bidRequest.adUnitCode, prebidBid);
           } else {
             logWarn(`Bidder ${spec.code} made bid for unknown request ID: ${bid.requestId}. Ignoring.`);
+            addBidResponse.reject(null, bid, CONSTANTS.REJECTION_REASON.INVALID_REQUEST_ID);
           }
         },
         onCompletion: afterAllResponses,
@@ -541,24 +545,22 @@ export function getIabSubCategory(bidderCode, category) {
 
 // check that the bid has a width and height set
 function validBidSize(adUnitCode, bid, {index = auctionManager.index} = {}) {
-  if ((bid.width || parseInt(bid.width, 10) === 0) && (bid.height || parseInt(bid.height, 10) === 0)) {
-    bid.width = parseInt(bid.width, 10);
-    bid.height = parseInt(bid.height, 10);
-    return true;
-  }
-
   const bidRequest = index.getBidRequest(bid);
   const mediaTypes = index.getMediaTypes(bid);
 
   const sizes = (bidRequest && bidRequest.sizes) || (mediaTypes && mediaTypes.banner && mediaTypes.banner.sizes);
-  const parsedSizes = parseSizesInput(sizes);
+  const parsedSizes = parseSizesInput(sizes).map(sz => sz.split('x').map(n => parseInt(n, 10)));
+
+  if ((bid.width || parseInt(bid.width, 10) === 0) && (bid.height || parseInt(bid.height, 10) === 0)) {
+    bid.width = parseInt(bid.width, 10);
+    bid.height = parseInt(bid.height, 10);
+    return parsedSizes.length === 0 || parsedSizes.some(([w, h]) => bid.width === w && bid.height === h);
+  }
 
   // if a banner impression has one valid size, we assign that size to any bid
   // response that does not explicitly set width or height
   if (parsedSizes.length === 1) {
-    const [ width, height ] = parsedSizes[0].split('x');
-    bid.width = parseInt(width, 10);
-    bid.height = parseInt(height, 10);
+    ([bid.width, bid.height] = parsedSizes[0]);
     return true;
   }
 
@@ -600,7 +602,7 @@ export function isValid(adUnitCode, bid, {index = auctionManager.index} = {}) {
     return false;
   }
   if (bid.mediaType === 'banner' && !validBidSize(adUnitCode, bid, {index})) {
-    logError(errorMessage(`Banner bids require a width and height`));
+    logError(errorMessage(`Banner bids require a width and height that match one of the requested sizes`));
     return false;
   }
 
diff --git a/src/auction.js b/src/auction.js
index 81280e0833c..26561d87d71 100644
--- a/src/auction.js
+++ b/src/auction.js
@@ -58,26 +58,41 @@
  */
 
 import {
-  flatten, timestamp, adUnitsFilter, deepAccess, getValue, parseUrl, generateUUID,
-  logMessage, bind, logError, logInfo, logWarn, isEmpty, _each, isFn, isEmptyStr
+  _each,
+  adUnitsFilter,
+  bind,
+  deepAccess,
+  flatten,
+  generateUUID,
+  getValue,
+  isEmpty,
+  isEmptyStr,
+  isFn,
+  logError,
+  logInfo,
+  logMessage,
+  logWarn,
+  parseUrl,
+  timestamp
 } from './utils.js';
-import { getPriceBucketString } from './cpmBucketManager.js';
-import { getNativeTargeting } from './native.js';
-import { getCacheUrl, store } from './videoCache.js';
-import { Renderer } from './Renderer.js';
-import { config } from './config.js';
-import { userSync } from './userSync.js';
-import { hook } from './hook.js';
+import {getPriceBucketString} from './cpmBucketManager.js';
+import {getNativeTargeting} from './native.js';
+import {getCacheUrl, store} from './videoCache.js';
+import {Renderer} from './Renderer.js';
+import {config} from './config.js';
+import {userSync} from './userSync.js';
+import {hook} from './hook.js';
 import {find, includes} from './polyfill.js';
-import { OUTSTREAM } from './video.js';
-import { VIDEO } from './mediaTypes.js';
+import {OUTSTREAM} from './video.js';
+import {VIDEO} from './mediaTypes.js';
 import {auctionManager} from './auctionManager.js';
 import {bidderSettings} from './bidderSettings.js';
-import * as events from './events.js'
+import * as events from './events.js';
 import adapterManager from './adapterManager.js';
 import CONSTANTS from './constants.json';
 import {GreedyPromise} from './utils/promise.js';
 import {useMetrics} from './utils/perfMetrics.js';
+import {createBid} from './bidfactory.js';
 
 const { syncUsers } = userSync;
 
@@ -119,24 +134,26 @@ export function resetAuctionState() {
   */
 export function newAuction({adUnits, adUnitCodes, callback, cbTimeout, labels, auctionId, ortb2Fragments, metrics}) {
   metrics = useMetrics(metrics);
-  let _adUnits = adUnits;
-  let _labels = labels;
-  let _adUnitCodes = adUnitCodes;
+  const _adUnits = adUnits;
+  const _labels = labels;
+  const _adUnitCodes = adUnitCodes;
+  const _auctionId = auctionId || generateUUID();
+  const _timeout = cbTimeout;
+  const _timelyBidders = new Set();
+  let _bidsRejected = [];
+  let _callback = callback;
   let _bidderRequests = [];
   let _bidsReceived = [];
   let _noBids = [];
+  let _winningBids = [];
   let _auctionStart;
   let _auctionEnd;
-  let _auctionId = auctionId || generateUUID();
-  let _auctionStatus;
-  let _callback = callback;
   let _timer;
-  let _timeout = cbTimeout;
-  let _winningBids = [];
-  let _timelyBidders = new Set();
+  let _auctionStatus;
 
   function addBidRequests(bidderRequests) { _bidderRequests = _bidderRequests.concat(bidderRequests); }
   function addBidReceived(bidsReceived) { _bidsReceived = _bidsReceived.concat(bidsReceived); }
+  function addBidRejected(bidsRejected) { _bidsRejected = _bidsRejected.concat(bidsRejected); }
   function addNoBid(noBid) { _noBids = _noBids.concat(noBid); }
 
   function getProperties() {
@@ -151,6 +168,7 @@ export function newAuction({adUnits, adUnitCodes, callback, cbTimeout, labels, a
       bidderRequests: _bidderRequests,
       noBids: _noBids,
       bidsReceived: _bidsReceived,
+      bidsRejected: _bidsRejected,
       winningBids: _winningBids,
       timeout: _timeout,
       metrics: metrics
@@ -352,6 +370,7 @@ export function newAuction({adUnits, adUnitCodes, callback, cbTimeout, labels, a
 
   return {
     addBidReceived,
+    addBidRejected,
     addNoBid,
     executeCallback,
     callBids,
@@ -372,7 +391,14 @@ export function newAuction({adUnits, adUnitCodes, callback, cbTimeout, labels, a
   };
 }
 
-export const addBidResponse = hook('sync', function(adUnitCode, bid) {
+/**
+ * Hook into this to intercept bids before they are added to an auction.
+ *
+ * @param adUnitCode
+ * @param bid
+ * @param {function(String)} reject: a function that, when called, rejects `bid` with the given reason.
+ */
+export const addBidResponse = hook('sync', function(adUnitCode, bid, reject) {
   this.dispatch.call(null, adUnitCode, bid);
 }, 'addBidResponse');
 
@@ -425,20 +451,49 @@ export function auctionCallbacks(auctionDone, auctionInstance, {index = auctionM
     }
   }
 
-  function handleBidResponse(adUnitCode, bid) {
+  function handleBidResponse(adUnitCode, bid, handler) {
     bidResponseMap[bid.requestId] = true;
-
+    addCommonResponseProperties(bid, adUnitCode)
     outstandingBidsAdded++;
-    let auctionId = auctionInstance.getAuctionId();
+    return handler(afterBidAdded);
+  }
 
-    let bidResponse = getPreparedBidForAuction({adUnitCode, bid, auctionId});
+  function acceptBidResponse(adUnitCode, bid) {
+    handleBidResponse(adUnitCode, bid, (done) => {
+      let bidResponse = getPreparedBidForAuction(bid);
 
-    if (bidResponse.mediaType === 'video') {
-      tryAddVideoBid(auctionInstance, bidResponse, afterBidAdded);
-    } else {
-      addBidToAuction(auctionInstance, bidResponse);
-      afterBidAdded();
-    }
+      if (bidResponse.mediaType === 'video') {
+        tryAddVideoBid(auctionInstance, bidResponse, done);
+      } else {
+        addBidToAuction(auctionInstance, bidResponse);
+        done();
+      }
+    });
+  }
+
+  function rejectBidResponse(adUnitCode, bid, reason) {
+    return handleBidResponse(adUnitCode, bid, (done) => {
+      // return a "NO_BID" replacement that the caller can decide to continue with
+      // TODO: remove this in v8; see https://github.com/prebid/Prebid.js/issues/8956
+      const noBid = createBid(CONSTANTS.STATUS.NO_BID, bid.getIdentifiers());
+      Object.assign(noBid, Object.fromEntries(Object.entries(bid).filter(([k]) => !noBid.hasOwnProperty(k) && ![
+        'ad',
+        'adUrl',
+        'vastXml',
+        'vastUrl',
+        'native',
+      ].includes(k))));
+      noBid.status = CONSTANTS.BID_STATUS.BID_REJECTED;
+      noBid.cpm = 0;
+
+      bid.rejectionReason = reason;
+      logWarn(`Bid from ${bid.bidder || 'unknown bidder'} was rejected: ${reason}`, bid)
+      events.emit(CONSTANTS.EVENTS.BID_REJECTED, bid);
+      auctionInstance.addBidRejected(bid);
+      done();
+
+      return noBid;
+    })
   }
 
   function adapterDone() {
@@ -470,12 +525,24 @@ export function auctionCallbacks(auctionDone, auctionInstance, {index = auctionM
   }
 
   return {
-    addBidResponse: function (adUnit, bid) {
-      const bidderRequest = index.getBidderRequest(bid);
-      waitFor((bidderRequest && bidderRequest.bidderRequestId) || '', addBidResponse.call({
-        dispatch: handleBidResponse,
-      }, adUnit, bid));
-    },
+    addBidResponse: (function () {
+      function addBid(adUnitCode, bid) {
+        const bidderRequest = index.getBidderRequest(bid);
+        waitFor((bidderRequest && bidderRequest.bidderRequestId) || '', addBidResponse.call({
+          dispatch: acceptBidResponse,
+        }, adUnitCode, bid, (() => {
+          let rejection;
+          return (reason) => {
+            if (rejection == null) {
+              rejection = rejectBidResponse(adUnitCode, bid, reason);
+            }
+            return rejection;
+          }
+        })()));
+      }
+      addBid.reject = rejectBidResponse;
+      return addBid;
+    })(),
     adapterDone: function () {
       guard(this, adapterDone.bind(this))
     }
@@ -492,9 +559,7 @@ export function doCallbacksIfTimedout(auctionInstance, bidResponse) {
 export function addBidToAuction(auctionInstance, bidResponse) {
   setupBidTargeting(bidResponse);
 
-  const metrics = useMetrics(bidResponse.metrics);
-  metrics.timeSince('addBidResponse', 'addBidResponse.total');
-
+  useMetrics(bidResponse.metrics).timeSince('addBidResponse', 'addBidResponse.total');
   events.emit(CONSTANTS.EVENTS.BID_RESPONSE, bidResponse);
   auctionInstance.addBidReceived(bidResponse);
 
@@ -595,35 +660,41 @@ export const callPrebidCache = hook('async', function(auctionInstance, bidRespon
   batchAndStore(auctionInstance, bidResponse, afterBidAdded);
 }, 'callPrebidCache');
 
-// Postprocess the bids so that all the universal properties exist, no matter which bidder they came from.
-// This should be called before addBidToAuction().
-function getPreparedBidForAuction({adUnitCode, bid, auctionId}, {index = auctionManager.index} = {}) {
-  const bidderRequest = index.getBidderRequest(bid);
-  const start = (bidderRequest && bidderRequest.start) || bid.requestTimestamp;
-
-  let bidObject = Object.assign({}, bid, {
-    auctionId,
-    responseTimestamp: timestamp(),
-    requestTimestamp: start,
-    cpm: parseFloat(bid.cpm) || 0,
-    bidder: bid.bidderCode,
+/**
+ * Augment `bidResponse` with properties that are common across all bids - including rejected bids.
+ *
+ */
+function addCommonResponseProperties(bidResponse, adUnitCode, {index = auctionManager.index} = {}) {
+  const bidderRequest = index.getBidderRequest(bidResponse);
+  const start = (bidderRequest && bidderRequest.start) || bidResponse.requestTimestamp;
+
+  Object.assign(bidResponse, {
+    responseTimestamp: bidResponse.responseTimestamp || timestamp(),
+    requestTimestamp: bidResponse.requestTimestamp || start,
+    cpm: bidResponse.cpm || parseFloat(bidResponse.cpm) || 0,
+    bidder: bidResponse.bidder || bidResponse.bidderCode,
     adUnitCode
   });
 
-  bidObject.timeToRespond = bidObject.responseTimestamp - bidObject.requestTimestamp;
+  bidResponse.timeToRespond = bidResponse.responseTimestamp - bidResponse.requestTimestamp;
+}
 
+/**
+ * Add additional bid response properties that are universal for all _accepted_ bids.
+ */
+function getPreparedBidForAuction(bid, {index = auctionManager.index} = {}) {
   // Let listeners know that now is the time to adjust the bid, if they want to.
   //
   // CAREFUL: Publishers rely on certain bid properties to be available (like cpm),
   // but others to not be set yet (like priceStrings). See #1372 and #1389.
-  events.emit(CONSTANTS.EVENTS.BID_ADJUSTMENT, bidObject);
+  events.emit(CONSTANTS.EVENTS.BID_ADJUSTMENT, bid);
 
   // a publisher-defined renderer can be used to render bids
-  const adUnitRenderer = index.getAdUnit(bidObject).renderer;
+  const adUnitRenderer = index.getAdUnit(bid).renderer;
 
   // a publisher can also define a renderer for a mediaType
-  const bidObjectMediaType = bidObject.mediaType;
-  const mediaTypes = index.getMediaTypes(bidObject);
+  const bidObjectMediaType = bid.mediaType;
+  const mediaTypes = index.getMediaTypes(bid);
   const bidMediaType = mediaTypes && mediaTypes[bidObjectMediaType];
 
   var mediaTypeRenderer = bidMediaType && bidMediaType.renderer;
@@ -639,25 +710,25 @@ function getPreparedBidForAuction({adUnitCode, bid, auctionId}, {index = auction
 
   if (renderer) {
     // be aware, an adapter could already have installed the bidder, in which case this overwrite's the existing adapter
-    bidObject.renderer = Renderer.install({ url: renderer.url, config: renderer.options });// rename options to config, to make it consistent?
-    bidObject.renderer.setRender(renderer.render);
+    bid.renderer = Renderer.install({ url: renderer.url, config: renderer.options });// rename options to config, to make it consistent?
+    bid.renderer.setRender(renderer.render);
   }
 
   // Use the config value 'mediaTypeGranularity' if it has been defined for mediaType, else use 'customPriceBucket'
   const mediaTypeGranularity = getMediaTypeGranularity(bid.mediaType, mediaTypes, config.getConfig('mediaTypePriceGranularity'));
   const priceStringsObj = getPriceBucketString(
-    bidObject.cpm,
+    bid.cpm,
     (typeof mediaTypeGranularity === 'object') ? mediaTypeGranularity : config.getConfig('customPriceBucket'),
     config.getConfig('currency.granularityMultiplier')
   );
-  bidObject.pbLg = priceStringsObj.low;
-  bidObject.pbMg = priceStringsObj.med;
-  bidObject.pbHg = priceStringsObj.high;
-  bidObject.pbAg = priceStringsObj.auto;
-  bidObject.pbDg = priceStringsObj.dense;
-  bidObject.pbCg = priceStringsObj.custom;
-
-  return bidObject;
+  bid.pbLg = priceStringsObj.low;
+  bid.pbMg = priceStringsObj.med;
+  bid.pbHg = priceStringsObj.high;
+  bid.pbAg = priceStringsObj.auto;
+  bid.pbDg = priceStringsObj.dense;
+  bid.pbCg = priceStringsObj.custom;
+
+  return bid;
 }
 
 function setupBidTargeting(bidObject) {
diff --git a/src/constants.json b/src/constants.json
index ad57fb45c4f..30ade5fccbe 100644
--- a/src/constants.json
+++ b/src/constants.json
@@ -29,6 +29,7 @@
     "BID_TIMEOUT": "bidTimeout",
     "BID_REQUESTED": "bidRequested",
     "BID_RESPONSE": "bidResponse",
+    "BID_REJECTED": "bidRejected",
     "NO_BID": "noBid",
     "BID_WON": "bidWon",
     "BIDDER_DONE": "bidderDone",
@@ -119,6 +120,13 @@
     "RENDERED": "rendered",
     "BID_REJECTED": "bidRejected"
   },
+  "REJECTION_REASON": {
+    "INVALID": "Bid has missing or invalid properties",
+    "INVALID_REQUEST_ID": "Invalid request ID",
+    "BIDDER_DISALLOWED": "Bidder code is not allowed by allowedAlternateBidderCodes / allowUnknownBidderCodes",
+    "FLOOR_NOT_MET": "Bid does not meet price floor",
+    "CANNOT_CONVERT_CURRENCY": "Unable to convert currency"
+  },
   "PREBID_NATIVE_DATA_KEYS_TO_ORTB": {
     "body": "desc",
     "body2": "desc2",
diff --git a/src/prebid.js b/src/prebid.js
index 18826fc7205..a0981cd387a 100644
--- a/src/prebid.js
+++ b/src/prebid.js
@@ -36,7 +36,7 @@ import {listenMessagesFromCreative} from './secureCreatives.js';
 import {userSync} from './userSync.js';
 import {config} from './config.js';
 import {auctionManager} from './auctionManager.js';
-import {filters, targeting} from './targeting.js';
+import {isBidUsable, targeting} from './targeting.js';
 import {hook, wrapHook} from './hook.js';
 import {loadSession} from './debugging.js';
 import {includes} from './polyfill.js';
@@ -296,8 +296,7 @@ $$PREBID_GLOBAL$$.getAdserverTargetingForAdUnitCodeStr = function (adunitCode) {
 $$PREBID_GLOBAL$$.getHighestUnusedBidResponseForAdUnitCode = function (adunitCode) {
   if (adunitCode) {
     const bid = auctionManager.getAllBidsForAdUnitCode(adunitCode)
-      .filter(filters.isUnusedBid)
-      .filter(filters.isBidNotExpired)
+      .filter(isBidUsable)
 
     return bid.length ? bid.reduce(getHighestCpm) : {}
   } else {
diff --git a/src/targeting.js b/src/targeting.js
index d2b3e9f8470..a427867e890 100644
--- a/src/targeting.js
+++ b/src/targeting.js
@@ -1,15 +1,28 @@
 import {
-  uniques, isGptPubadsDefined, getHighestCpm, getOldestHighestCpmBid, groupBy, isAdUnitCodeMatchingSlot, timestamp,
-  deepAccess, deepClone, logError, logWarn, logInfo, isFn, isArray, logMessage, isStr,
+  deepAccess,
+  deepClone,
+  getHighestCpm,
+  getOldestHighestCpmBid,
+  groupBy,
+  isAdUnitCodeMatchingSlot,
+  isArray,
+  isFn,
+  isGptPubadsDefined,
+  isStr,
+  logError,
+  logInfo,
+  logMessage,
+  logWarn,
+  timestamp,
+  uniques,
 } from './utils.js';
-import { config } from './config.js';
-import { NATIVE_TARGETING_KEYS } from './native.js';
-import { auctionManager } from './auctionManager.js';
-import { sizeSupported } from './sizeMapping.js';
-import { ADPOD } from './mediaTypes.js';
-import { hook } from './hook.js';
-import { bidderSettings } from './bidderSettings.js';
-import {includes, find} from './polyfill.js';
+import {config} from './config.js';
+import {NATIVE_TARGETING_KEYS} from './native.js';
+import {auctionManager} from './auctionManager.js';
+import {ADPOD} from './mediaTypes.js';
+import {hook} from './hook.js';
+import {bidderSettings} from './bidderSettings.js';
+import {find, includes} from './polyfill.js';
 import CONSTANTS from './constants.json';
 
 var pbTargetingKeys = [];
@@ -32,10 +45,17 @@ const isBidNotExpired = (bid) => (bid.responseTimestamp + bid.ttl * 1000 - TTL_B
 const isUnusedBid = (bid) => bid && ((bid.status && !includes([CONSTANTS.BID_STATUS.RENDERED], bid.status)) || !bid.status);
 
 export let filters = {
+  isActualBid(bid) {
+    return bid.getStatusCode() === CONSTANTS.STATUS.GOOD
+  },
   isBidNotExpired,
   isUnusedBid
 };
 
+export function isBidUsable(bid) {
+  return !Object.values(filters).some((predicate) => !predicate(bid));
+}
+
 // If two bids are found for same adUnitCode, we will use the highest one to take part in auction
 // This can happen in case of concurrent auctions
 // If adUnitBidLimit is set above 0 return top N number of bids
@@ -449,10 +469,7 @@ export function newTargeting(auctionManager) {
 
     bidsReceived = bidsReceived
       .filter(bid => deepAccess(bid, 'video.context') !== ADPOD)
-      .filter(bid => bid.mediaType !== 'banner' || sizeSupported([bid.width, bid.height]))
-      .filter(filters.isUnusedBid)
-      .filter(filters.isBidNotExpired)
-    ;
+      .filter(isBidUsable);
 
     return getHighestCpmBidsFromBidPool(bidsReceived, getOldestHighestCpmBid);
   }
diff --git a/test/fixtures/fixtures.js b/test/fixtures/fixtures.js
index b0fbd7da806..b66d885c113 100644
--- a/test/fixtures/fixtures.js
+++ b/test/fixtures/fixtures.js
@@ -1,5 +1,6 @@
 // jscs:disable
 import CONSTANTS from 'src/constants.json';
+import {createBid} from '../../src/bidfactory.js';
 const utils = require('src/utils.js');
 
 function convertTargetingsFromOldToNew(targetings) {
@@ -1268,7 +1269,7 @@ export function createBidReceived({bidder, cpm, auctionId, responseTimestamp, ad
   if (typeof status !== 'undefined') {
     bid.status = status;
   }
-  return bid;
+  return Object.assign(createBid(CONSTANTS.STATUS.GOOD), bid);
 }
 
 export function getServerTestingsAds() {
diff --git a/test/spec/auctionmanager_spec.js b/test/spec/auctionmanager_spec.js
index 49ae13c43cc..105401a62a4 100644
--- a/test/spec/auctionmanager_spec.js
+++ b/test/spec/auctionmanager_spec.js
@@ -21,6 +21,7 @@ import {auctionManager} from '../../src/auctionManager.js';
 import 'modules/debugging/index.js' // some tests look for debugging side effects
 import {AuctionIndex} from '../../src/auctionIndex.js';
 import {expect} from 'chai';
+import {deepClone} from '../../src/utils.js';
 
 var assert = require('assert');
 
@@ -57,7 +58,16 @@ function mockBid(opts) {
     'currency': 'USD',
     'netRevenue': true,
     'ttl': 360,
-    getSize: () => '300x250'
+    getSize: () => '300x250',
+    getIdentifiers() {
+      return {
+        src: this.source,
+        bidder: this.bidderCode,
+        bidId: this.requestId,
+        transactionId: this.transactionId,
+        auctionId: this.auctionId
+      }
+    }
   };
 }
 
@@ -1323,6 +1333,7 @@ describe('auctionmanager.js', function () {
       getAdUnits: () => getBidRequests().flatMap(br => br.bids).map(br => ({ code: br.adUnitCode, transactionId: br.transactionId, mediaTypes: br.mediaTypes })),
       getAuctionId: () => '1',
       addBidReceived: () => true,
+      addBidRejected: () => true,
       getTimeout: () => 1000,
       getAuctionStart: () => start,
     }
@@ -1382,26 +1393,32 @@ describe('auctionmanager.js', function () {
       bidRequests = null;
     });
 
-    it('should call auction done after bid is added to auction for mediaType banner', function () {
-      let ADUNIT_CODE2 = 'adUnitCode2';
-      let BIDDER_CODE2 = 'sampleBidder2';
-
-      let bids1 = [mockBid({ bidderCode: BIDDER_CODE1, transactionId: ADUNIT_CODE1 })];
-      let bids2 = [mockBid({ bidderCode: BIDDER_CODE2, transactionId: ADUNIT_CODE2 })];
-      bidRequests = [
-        mockBidRequest(bids[0]),
-        mockBidRequest(bids1[0], { adUnitCode: ADUNIT_CODE1 }),
-        mockBidRequest(bids2[0], { adUnitCode: ADUNIT_CODE2 })
-      ];
-      let cbs = auctionCallbacks(doneSpy, auction);
-      cbs.addBidResponse.call(bidRequests[0], ADUNIT_CODE, bids[0]);
-      cbs.adapterDone.call(bidRequests[0]);
-      cbs.addBidResponse.call(bidRequests[1], ADUNIT_CODE1, bids1[0]);
-      cbs.adapterDone.call(bidRequests[1]);
-      cbs.addBidResponse.call(bidRequests[2], ADUNIT_CODE2, bids2[0]);
-      cbs.adapterDone.call(bidRequests[2]);
-      assert.equal(doneSpy.callCount, 1);
-    });
+    Object.entries({
+      'added to': (cbs) => cbs.addBidResponse,
+      'rejected from': (cbs) => cbs.addBidResponse.reject,
+    }).forEach(([t, getMethod]) => {
+      it(`should call auction done after bid is ${t} auction for mediaType banner`, function () {
+        let ADUNIT_CODE2 = 'adUnitCode2';
+        let BIDDER_CODE2 = 'sampleBidder2';
+
+        let bids1 = [mockBid({ bidderCode: BIDDER_CODE1, transactionId: ADUNIT_CODE1 })];
+        let bids2 = [mockBid({ bidderCode: BIDDER_CODE2, transactionId: ADUNIT_CODE2 })];
+        bidRequests = [
+          mockBidRequest(bids[0]),
+          mockBidRequest(bids1[0], { adUnitCode: ADUNIT_CODE1 }),
+          mockBidRequest(bids2[0], { adUnitCode: ADUNIT_CODE2 })
+        ];
+        let cbs = auctionCallbacks(doneSpy, auction);
+        const method = getMethod(cbs);
+        method(ADUNIT_CODE, bids[0]);
+        cbs.adapterDone.call(bidRequests[0]);
+        method(ADUNIT_CODE1, bids1[0]);
+        cbs.adapterDone.call(bidRequests[1]);
+        method(ADUNIT_CODE2, bids2[0]);
+        cbs.adapterDone.call(bidRequests[2]);
+        assert.equal(doneSpy.callCount, 1);
+      });
+    })
 
     it('should call auction done after prebid cache is complete for mediaType video', function() {
       bids[0].mediaType = 'video';
@@ -1543,6 +1560,77 @@ describe('auctionmanager.js', function () {
         });
       })
     });
+
+    describe('when bids are rejected', () => {
+      let cbs, bid, expectedRejection;
+      const onBidRejected = sinon.stub();
+      const REJECTION_REASON = 'Bid rejected';
+      const AU_CODE = 'au';
+
+      function rejectHook(fn, adUnitCode, bid, reject) {
+        reject(REJECTION_REASON);
+        reject(REJECTION_REASON); // second call should do nothing
+      }
+
+      before(() => {
+        addBidResponse.before(rejectHook, 999);
+        events.on(CONSTANTS.EVENTS.BID_REJECTED, onBidRejected);
+      });
+
+      after(() => {
+        addBidResponse.getHooks({hook: rejectHook}).remove();
+        events.off(CONSTANTS.EVENTS.BID_REJECTED, onBidRejected);
+      });
+
+      beforeEach(() => {
+        onBidRejected.reset();
+        bid = mockBid({bidderCode: BIDDER_CODE});
+        bidRequests = [
+          mockBidRequest(bid),
+        ];
+        cbs = auctionCallbacks(doneSpy, auction);
+        expectedRejection = sinon.match(Object.assign({}, bid, {
+          rejectionReason: REJECTION_REASON,
+          adUnitCode: AU_CODE
+        }));
+        auction.addBidRejected = sinon.stub();
+      });
+
+      Object.entries({
+        'with addBidResponse.reject': () => cbs.addBidResponse.reject(AU_CODE, deepClone(bid), REJECTION_REASON),
+        'from addBidResponse hooks': () => cbs.addBidResponse(AU_CODE, deepClone(bid))
+      }).forEach(([t, rejectBid]) => {
+        describe(t, () => {
+          it('should emit a BID_REJECTED event', () => {
+            rejectBid();
+            sinon.assert.calledWith(onBidRejected, expectedRejection);
+          });
+
+          it('should pass bid to auction.addBidRejected', () => {
+            rejectBid();
+            sinon.assert.calledWith(auction.addBidRejected, expectedRejection);
+          });
+        })
+      });
+
+      it('should return a NO_BID replacement', () => {
+        const noBid = cbs.addBidResponse.reject(AU_CODE, {...bid, statusMessage: 'Bid available', status: CONSTANTS.BID_STATUS.RENDERED}, 'Rejected');
+        sinon.assert.match(noBid, {
+          status: CONSTANTS.BID_STATUS.BID_REJECTED,
+          statusMessage: 'Bid returned empty or error response',
+          cpm: 0,
+          requestId: bid.requestId,
+          auctionId: bid.auctionId,
+          adUnitCode: AU_CODE,
+          rejectionReason: undefined,
+        });
+      });
+
+      it('addBidResponse hooks should not be able to reject the same bid twice', () => {
+        cbs.addBidResponse(AU_CODE, bid);
+        expect(auction.addBidRejected.calledOnce).to.be.true;
+      });
+    })
   });
 
   describe('auctionOptions', function() {
diff --git a/test/spec/modules/currency_spec.js b/test/spec/modules/currency_spec.js
index 6eb4f929a42..b674cb5976d 100644
--- a/test/spec/modules/currency_spec.js
+++ b/test/spec/modules/currency_spec.js
@@ -351,6 +351,11 @@ describe('currency', function () {
   });
 
   describe('currency.addBidResponseDecorator', function () {
+    let reject;
+    beforeEach(() => {
+      reject = sinon.stub().returns({status: 'rejected'});
+    });
+
     it('should leave bid at 1 when currency support is not enabled and fromCurrency is USD', function () {
       setConfig({});
       var bid = makeBid({ 'cpm': 1, 'currency': 'USD' });
@@ -368,8 +373,9 @@ describe('currency', function () {
       var innerBid;
       addBidResponseHook(function(adCodeId, bid) {
         innerBid = bid;
-      }, 'elementId', bid);
-      expect(innerBid.statusMessage).to.equal('Bid returned empty or error response');
+      }, 'elementId', bid, reject);
+      expect(innerBid.status).to.equal('rejected');
+      expect(reject.calledOnce).to.be.true;
     });
 
     it('should not buffer bid when currency is already in desired currency', function () {
@@ -395,8 +401,9 @@ describe('currency', function () {
       var innerBid;
       addBidResponseHook(function(adCodeId, bid) {
         innerBid = bid;
-      }, 'elementId', bid);
-      expect(innerBid.statusMessage).to.equal('Bid returned empty or error response');
+      }, 'elementId', bid, reject);
+      expect(innerBid.status).to.equal('rejected');
+      expect(reject.calledOnce).to.be.true;
     });
 
     it('should result in NO_BID when adServerCurrency is not supported in file', function () {
@@ -407,8 +414,9 @@ describe('currency', function () {
       var innerBid;
       addBidResponseHook(function(adCodeId, bid) {
         innerBid = bid;
-      }, 'elementId', bid);
-      expect(innerBid.statusMessage).to.equal('Bid returned empty or error response');
+      }, 'elementId', bid, reject);
+      expect(innerBid.status).to.equal('rejected');
+      expect(reject.calledOnce).to.be.true;
     });
 
     it('should return 1 when currency support is enabled and same currency code is requested as is set to adServerCurrency', function () {
diff --git a/test/spec/modules/prebidServerBidAdapter_spec.js b/test/spec/modules/prebidServerBidAdapter_spec.js
index c3ca3261193..b5209e5be12 100644
--- a/test/spec/modules/prebidServerBidAdapter_spec.js
+++ b/test/spec/modules/prebidServerBidAdapter_spec.js
@@ -536,6 +536,8 @@ describe('S2S Adapter', function () {
     addBidResponse = sinon.spy(),
     done = sinon.spy();
 
+  addBidResponse.reject = sinon.spy();
+
   function prepRequest(req) {
     req.ad_units.forEach((adUnit) => {
       delete adUnit.nativeParams
@@ -595,6 +597,7 @@ describe('S2S Adapter', function () {
 
   afterEach(function () {
     addBidResponse.resetHistory();
+    addBidResponse.reject = sinon.spy();
     done.resetHistory();
   });
 
@@ -2903,6 +2906,16 @@ describe('S2S Adapter', function () {
       });
     }
 
+    it('should reject invalid bids', () => {
+      config.setConfig({ s2sConfig: CONFIG });
+      adapter.callBids(REQUEST, BID_REQUESTS, addBidResponse, done, ajax);
+      const response = deepClone(RESPONSE_OPENRTB);
+      Object.assign(response.seatbid[0].bid[0], {w: null, h: null});
+      server.requests[0].respond(200, {}, JSON.stringify(response));
+      expect(addBidResponse.reject.calledOnce).to.be.true;
+      expect(addBidResponse.called).to.be.false;
+    });
+
     it('does not (by default) allow bids that were not requested', function () {
       config.setConfig({ s2sConfig: CONFIG });
       adapter.callBids(REQUEST, BID_REQUESTS, addBidResponse, done, ajax);
@@ -2911,6 +2924,7 @@ describe('S2S Adapter', function () {
       server.requests[0].respond(200, {}, JSON.stringify(response));
 
       expect(addBidResponse.called).to.be.false;
+      expect(addBidResponse.reject.calledOnce).to.be.true;
     });
 
     it('allows unrequested bids if config.allowUnknownBidderCodes', function () {
@@ -2924,17 +2938,35 @@ describe('S2S Adapter', function () {
       expect(addBidResponse.calledWith(sinon.match.any, sinon.match({ bidderCode: 'unknown' }))).to.be.true;
     });
 
-    it('uses "null" request\'s ID for all responses, when a null request is present', function () {
-      const cfg = {...CONFIG, allowUnknownBidderCodes: true};
-      config.setConfig({s2sConfig: cfg});
-      const req = {...REQUEST, s2sConfig: cfg, ad_units: [{...REQUEST.ad_units[0], bids: [{bidder: null, bid_id: 'testId'}]}]};
-      const bidReq = {...BID_REQUESTS[0], bidderCode: null, bids: [{...BID_REQUESTS[0].bids[0], bidder: null, bidId: 'testId'}]}
-      adapter.callBids(req, [bidReq], addBidResponse, done, ajax);
-      const response = deepClone(RESPONSE_OPENRTB);
-      response.seatbid[0].seat = 'storedImpression';
-      server.requests[0].respond(200, {}, JSON.stringify(response));
-      sinon.assert.calledWith(addBidResponse, sinon.match.any, sinon.match({bidderCode: 'storedImpression', requestId: 'testId'}))
-    });
+    describe('stored impressions', () => {
+      let bidReq, response;
+
+      function mks2sReq(s2sConfig = CONFIG) {
+        return {...REQUEST, s2sConfig, ad_units: [{...REQUEST.ad_units[0], bids: [{bidder: null, bid_id: 'testId'}]}]};
+      }
+
+      beforeEach(() => {
+        bidReq = {...BID_REQUESTS[0], bidderCode: null, bids: [{...BID_REQUESTS[0].bids[0], bidder: null, bidId: 'testId'}]}
+        response = deepClone(RESPONSE_OPENRTB);
+        response.seatbid[0].seat = 'storedImpression';
+      })
+
+      it('uses "null" request\'s ID for all responses, when a null request is present', function () {
+        const cfg = {...CONFIG, allowUnknownBidderCodes: true};
+        config.setConfig({s2sConfig: cfg});
+        adapter.callBids(mks2sReq(cfg), [bidReq], addBidResponse, done, ajax);
+        server.requests[0].respond(200, {}, JSON.stringify(response));
+        sinon.assert.calledWith(addBidResponse, sinon.match.any, sinon.match({bidderCode: 'storedImpression', requestId: 'testId'}))
+      });
+
+      it('does not allow null requests (= stored impressions) if allowUnknownBidderCodes is not set', () => {
+        config.setConfig({s2sConfig: CONFIG});
+        adapter.callBids(mks2sReq(), [bidReq], addBidResponse, done, ajax);
+        server.requests[0].respond(200, {}, JSON.stringify(response));
+        expect(addBidResponse.called).to.be.false;
+        expect(addBidResponse.reject.calledOnce).to.be.true;
+      });
+    })
 
     it('copies ortb2Imp to response when there is only a null bid', () => {
       const cfg = {...CONFIG};
diff --git a/test/spec/modules/priceFloors_spec.js b/test/spec/modules/priceFloors_spec.js
index cbdd4d179e3..b7d771814d0 100644
--- a/test/spec/modules/priceFloors_spec.js
+++ b/test/spec/modules/priceFloors_spec.js
@@ -1665,7 +1665,7 @@ describe('the price floors module', function () {
   });
   describe('bidResponseHook tests', function () {
     const AUCTION_ID = '123456';
-    let returnedBidResponse, indexStub;
+    let returnedBidResponse, indexStub, reject;
     let adUnit = {
       transactionId: 'au',
       code: 'test_div_1'
@@ -1681,6 +1681,7 @@ describe('the price floors module', function () {
     };
     beforeEach(function () {
       returnedBidResponse = {};
+      reject = sinon.stub().returns({status: 'rejected'});
       indexStub = sinon.stub(auctionManager, 'index');
       indexStub.get(() => stubAuctionIndex({adUnits: [adUnit]}));
     });
@@ -1693,7 +1694,7 @@ describe('the price floors module', function () {
       let next = (adUnitCode, bid) => {
         returnedBidResponse = bid;
       };
-      addBidResponseHook(next, bidResp.adUnitCode, Object.assign(createBid(CONSTANTS.STATUS.GOOD, {auctionId: AUCTION_ID}), bidResp));
+      addBidResponseHook(next, bidResp.adUnitCode, Object.assign(createBid(CONSTANTS.STATUS.GOOD, {auctionId: AUCTION_ID}), bidResp), reject);
     };
     it('continues with the auction if not floors data is present without any flooring', function () {
       runBidResponse();
@@ -1710,9 +1711,8 @@ describe('the price floors module', function () {
       _floorDataForAuction[AUCTION_ID] = utils.deepClone(basicFloorConfig);
       _floorDataForAuction[AUCTION_ID].data.values = { 'banner': 1.0 };
       runBidResponse();
-      expect(returnedBidResponse).to.haveOwnProperty('floorData');
-      expect(returnedBidResponse.status).to.equal(CONSTANTS.BID_STATUS.BID_REJECTED);
-      expect(returnedBidResponse.cpm).to.equal(0);
+      expect(reject.calledOnce).to.be.true;
+      expect(returnedBidResponse.status).to.equal('rejected');
     });
     it('if it finds a rule and does not floor should update the bid accordingly', function () {
       _floorDataForAuction[AUCTION_ID] = utils.deepClone(basicFloorConfig);
diff --git a/test/spec/unit/core/bidderFactory_spec.js b/test/spec/unit/core/bidderFactory_spec.js
index 7164e468e71..fa6cf7e6bb5 100644
--- a/test/spec/unit/core/bidderFactory_spec.js
+++ b/test/spec/unit/core/bidderFactory_spec.js
@@ -1,4 +1,4 @@
-import { newBidder, registerBidder, preloadBidderMappingFile, storage } from 'src/adapters/bidderFactory.js';
+import {newBidder, registerBidder, preloadBidderMappingFile, storage, isValid} from 'src/adapters/bidderFactory.js';
 import adapterManager from 'src/adapterManager.js';
 import * as ajax from 'src/ajax.js';
 import { expect } from 'chai';
@@ -62,6 +62,7 @@ describe('bidders created by newBidder', function () {
     };
 
     addBidResponseStub = sinon.stub();
+    addBidResponseStub.reject = sinon.stub();
     doneStub = sinon.stub();
   });
 
@@ -508,7 +509,7 @@ describe('bidders created by newBidder', function () {
       expect(userSyncStub.firstCall.args[2]).to.equal('usersync.com');
     });
 
-    it('should logError when required bid response params are missing', function () {
+    it('should logError and reject bid when required bid response params are missing', function () {
       const bidder = newBidder(spec);
 
       const bid = {
@@ -532,9 +533,10 @@ describe('bidders created by newBidder', function () {
       bidder.callBids(MOCK_BIDS_REQUEST, addBidResponseStub, doneStub, ajaxStub, onTimelyResponseStub, wrappedCallback);
 
       expect(logErrorSpy.calledOnce).to.equal(true);
+      expect(addBidResponseStub.reject.calledOnce).to.be.true;
     });
 
-    it('should logError when required bid response params are undefined', function () {
+    it('should logError and reject bid when required response params are undefined', function () {
       const bidder = newBidder(spec);
 
       const bid = {
@@ -562,6 +564,7 @@ describe('bidders created by newBidder', function () {
       bidder.callBids(MOCK_BIDS_REQUEST, addBidResponseStub, doneStub, ajaxStub, onTimelyResponseStub, wrappedCallback);
 
       expect(logErrorSpy.calledOnce).to.equal(true);
+      expect(addBidResponseStub.reject.calledOnce).to.be.true;
     });
 
     it('should require requestId from interpretResponse', () => {
@@ -586,6 +589,7 @@ describe('bidders created by newBidder', function () {
       bidder.callBids(MOCK_BIDS_REQUEST, addBidResponseStub, doneStub, ajaxStub, onTimelyResponseStub, wrappedCallback);
 
       expect(addBidResponseStub.called).to.be.false;
+      expect(addBidResponseStub.reject.calledOnce).to.be.true;
     });
   });
 
@@ -856,6 +860,7 @@ describe('validate bid response: ', function () {
     });
 
     addBidResponseStub = sinon.stub();
+    addBidResponseStub.reject = sinon.stub();
     doneStub = sinon.stub();
     ajaxStub = sinon.stub(ajax, 'ajax').callsFake(function(url, callbacks) {
       const fakeResponse = sinon.stub();
@@ -954,7 +959,8 @@ describe('validate bid response: ', function () {
       spec.interpretResponse.returns(bids1);
       bidder.callBids(bidRequest, addBidResponseStub, doneStub, ajaxStub, onTimelyResponseStub, wrappedCallback);
 
-      expect(addBidResponseStub.calledOnce).to.equal(false);
+      expect(addBidResponseStub.called).to.equal(false);
+      expect(addBidResponseStub.reject.calledOnce).to.be.true;
       expect(logErrorSpy.calledWithMatch('Ignoring bid: Native bid missing some required properties.')).to.equal(true);
     });
   }
@@ -1074,7 +1080,8 @@ describe('validate bid response: ', function () {
       spec.interpretResponse.returns(bids1);
       bidder.callBids(bidRequest, addBidResponseStub, doneStub, ajaxStub, onTimelyResponseStub, wrappedCallback);
 
-      expect(addBidResponseStub.calledOnce).to.equal(false);
+      expect(addBidResponseStub.called).to.equal(false);
+      expect(addBidResponseStub.reject.calledOnce).to.be.true;
       expect(logWarnSpy.callCount).to.equal(1);
     });
 
@@ -1085,7 +1092,8 @@ describe('validate bid response: ', function () {
       spec.interpretResponse.returns(bids1);
       bidder.callBids(bidRequest, addBidResponseStub, doneStub, ajaxStub, onTimelyResponseStub, wrappedCallback);
 
-      expect(addBidResponseStub.calledOnce).to.equal(false);
+      expect(addBidResponseStub.called).to.equal(false);
+      expect(addBidResponseStub.reject.calledOnce).to.be.true;
     });
 
     it('should log warning when the particular bidder is not specified in allowedAlternateBidderCodes and allowAlternateBidderCodes flag is true', function () {
@@ -1096,7 +1104,8 @@ describe('validate bid response: ', function () {
       spec.interpretResponse.returns(bids1);
       bidder.callBids(bidRequest, addBidResponseStub, doneStub, ajaxStub, onTimelyResponseStub, wrappedCallback);
 
-      expect(addBidResponseStub.calledOnce).to.equal(false);
+      expect(addBidResponseStub.called).to.equal(false);
+      expect(addBidResponseStub.reject.calledOnce).to.be.true;
       expect(logWarnSpy.callCount).to.equal(1);
     });
 
@@ -1147,7 +1156,8 @@ describe('validate bid response: ', function () {
       spec.interpretResponse.returns(bids1);
       bidder.callBids(bidRequest, addBidResponseStub, doneStub, ajaxStub, onTimelyResponseStub, wrappedCallback);
 
-      expect(addBidResponseStub.calledOnce).to.equal(false);
+      expect(addBidResponseStub.called).to.equal(false);
+      expect(addBidResponseStub.reject.calledOnce).to.be.true;
       expect(logWarnSpy.callCount).to.equal(1);
     });
 
@@ -1159,7 +1169,7 @@ describe('validate bid response: ', function () {
       spec.interpretResponse.returns(bids1);
       bidder.callBids(bidRequest, addBidResponseStub, doneStub, ajaxStub, onTimelyResponseStub, wrappedCallback);
 
-      expect(addBidResponseStub.calledOnce).to.equal(true);
+      expect(addBidResponseStub.called).to.equal(true);
       expect(logWarnSpy.callCount).to.equal(0);
       expect(logErrorSpy.callCount).to.equal(0);
     });
@@ -1172,8 +1182,9 @@ describe('validate bid response: ', function () {
       spec.interpretResponse.returns(bids1);
       bidder.callBids(bidRequest, addBidResponseStub, doneStub, ajaxStub, onTimelyResponseStub, wrappedCallback);
 
-      expect(addBidResponseStub.calledOnce).to.equal(false);
+      expect(addBidResponseStub.called).to.equal(false);
       expect(logWarnSpy.callCount).to.equal(1);
+      expect(addBidResponseStub.reject.calledOnce).to.be.true;
     });
 
     it('should not accept the bid, when bidderSetting is missing for the bidder. It should fallback to standard setting and reject the bid', function () {
@@ -1183,7 +1194,8 @@ describe('validate bid response: ', function () {
       spec.interpretResponse.returns(bids1);
       bidder.callBids(bidRequest, addBidResponseStub, doneStub, ajaxStub, onTimelyResponseStub, wrappedCallback);
 
-      expect(addBidResponseStub.calledOnce).to.equal(false);
+      expect(addBidResponseStub.called).to.equal(false);
+      expect(addBidResponseStub.reject.calledOnce).to.be.true;
       expect(logWarnSpy.callCount).to.equal(1);
     });
   });
@@ -1385,3 +1397,46 @@ describe('preload mapping url hook', function() {
     clock.restore();
   });
 });
+
+describe('bid response isValid', () => {
+  describe('size check', () => {
+    let req, index;
+
+    beforeEach(() => {
+      req = {
+        ...MOCK_BIDS_REQUEST.bids[0],
+        mediaTypes: {
+          banner: {
+            sizes: [[1, 2], [3, 4]]
+          }
+        }
+      }
+    });
+
+    function mkResponse(width, height) {
+      return {
+        requestId: req.bidId,
+        width,
+        height,
+        cpm: 1,
+        ttl: 60,
+        creativeId: '123',
+        netRevenue: true,
+        currency: 'USD',
+        mediaType: 'banner',
+      }
+    }
+
+    function checkValid(bid) {
+      return isValid('au', bid, {index: stubAuctionIndex({bidRequests: [req]})});
+    }
+
+    it('should succeed when response has a size that was in request', () => {
+      expect(checkValid(mkResponse(3, 4))).to.be.true;
+    });
+
+    it('should fail when response has a size that was not in request', () => {
+      expect(checkValid(mkResponse(10, 11))).to.be.false;
+    });
+  })
+});
diff --git a/test/spec/unit/core/targeting_spec.js b/test/spec/unit/core/targeting_spec.js
index 4585ddbfaaf..448f1b36e3a 100644
--- a/test/spec/unit/core/targeting_spec.js
+++ b/test/spec/unit/core/targeting_spec.js
@@ -6,8 +6,14 @@ import CONSTANTS from 'src/constants.json';
 import { auctionManager } from 'src/auctionManager.js';
 import * as utils from 'src/utils.js';
 import {deepClone} from 'src/utils.js';
+import {createBid} from '../../../../src/bidfactory.js';
+import {hook} from '../../../../src/hook.js';
 
-const bid1 = {
+function mkBid(bid, status = CONSTANTS.STATUS.GOOD) {
+  return Object.assign(createBid(status), bid);
+}
+
+const sampleBid = {
   'bidderCode': 'rubicon',
   'width': '300',
   'height': '250',
@@ -39,7 +45,9 @@ const bid1 = {
   'ttl': 300
 };
 
-const bid2 = {
+const bid1 = mkBid(sampleBid);
+
+const bid2 = mkBid({
   'bidderCode': 'rubicon',
   'width': '300',
   'height': '250',
@@ -67,9 +75,9 @@ const bid2 = {
   'netRevenue': true,
   'currency': 'USD',
   'ttl': 300
-};
+});
 
-const bid3 = {
+const bid3 = mkBid({
   'bidderCode': 'rubicon',
   'width': '300',
   'height': '600',
@@ -97,9 +105,9 @@ const bid3 = {
   'netRevenue': true,
   'currency': 'USD',
   'ttl': 300
-};
+});
 
-const nativeBid1 = {
+const nativeBid1 = mkBid({
   'bidderCode': 'appnexus',
   'width': 0,
   'height': 0,
@@ -165,8 +173,9 @@ const nativeBid1 = {
     [CONSTANTS.NATIVE_KEYS.image]: 'http://vcdn.adnxs.com/p/creative-image/94/22/cd/0f/9422cd0f-f400-45d3-80f5-2b92629d9257.jpg',
     [CONSTANTS.NATIVE_KEYS.icon]: 'http://vcdn.adnxs.com/p/creative-image/bd/59/a6/c6/bd59a6c6-0851-411d-a16d-031475a51312.png'
   }
-};
-const nativeBid2 = {
+});
+
+const nativeBid2 = mkBid({
   'bidderCode': 'dgads',
   'width': 0,
   'height': 0,
@@ -222,7 +231,7 @@ const nativeBid2 = {
     [CONSTANTS.NATIVE_KEYS.sponsoredBy]: 'test.com',
     [CONSTANTS.NATIVE_KEYS.clickUrl]: 'http://prebid.org/'
   }
-};
+});
 
 describe('targeting tests', function () {
   let sandbox;
@@ -231,6 +240,10 @@ describe('targeting tests', function () {
   let bidCacheFilterFunction;
   let undef;
 
+  before(() => {
+    hook.ready();
+  });
+
   beforeEach(function() {
     sandbox = sinon.sandbox.create();
 
@@ -287,6 +300,12 @@ describe('targeting tests', function () {
       bidExpiryStub.restore();
     });
 
+    it('should filter out NO_BID bids', () => {
+      bidsReceived = [mkBid(sampleBid, CONSTANTS.STATUS.NO_BID)];
+      const tg = targetingInstance.getAllTargeting();
+      expect(tg[bidsReceived[0].adUnitCode]).to.eql({});
+    });
+
     describe('when handling different adunit targeting value types', function () {
       const adUnitCode = '/123456/header-bid-tag-0';
       const adServerTargeting = {};
diff --git a/test/spec/unit/pbjs_api_spec.js b/test/spec/unit/pbjs_api_spec.js
index 6757ef42094..aac36ee76a1 100644
--- a/test/spec/unit/pbjs_api_spec.js
+++ b/test/spec/unit/pbjs_api_spec.js
@@ -200,6 +200,7 @@ describe('Unit: Prebid Module', function () {
     hook.ready();
     $$PREBID_GLOBAL$$.requestBids.getHooks().remove();
     resetDebugging();
+    sinon.stub(filters, 'isActualBid').returns(true); // stub this out so that we can use vanilla objects as bids
   });
 
   beforeEach(function () {
@@ -216,6 +217,7 @@ describe('Unit: Prebid Module', function () {
 
   after(function() {
     auctionManager.clearAllAuctions();
+    filters.isActualBid.restore();
   });
 
   describe('and global adUnits', () => {
@@ -504,8 +506,8 @@ describe('Unit: Prebid Module', function () {
           'client_initiated_ad_counting': true,
           'rtb': {
             'banner': {
-              'width': 728,
-              'height': 90,
+              'width': 300,
+              'height': 250,
               'content': '<!-- Creative -->'
             },
             'trackers': [{