diff --git a/modules/ixBidAdapter.js b/modules/ixBidAdapter.js
index 77d4220e59a..cb37e4735c5 100644
--- a/modules/ixBidAdapter.js
+++ b/modules/ixBidAdapter.js
@@ -235,9 +235,9 @@ function addUserEids(userEids, seenIdPartners, id, source, ixlPartnerName, rtiPa
  *
  * @param  {array}  validBidRequests A list of valid bid request config objects.
  * @param  {object} bidderRequest    An object containing other info like gdprConsent.
- * @param  {array}  impressions      List of impression objects describing the bids.
+ * @param  {object} impressions      An object containing a list of impression objects describing the bids for each transactionId
  * @param  {array}  version          Endpoint version denoting banner or video.
- * @return {object}                  Info describing the request to the server.
+ * @return {array}                   List of objects describing the request to the server.
  *
  */
 function buildRequest(validBidRequests, bidderRequest, impressions, version) {
@@ -280,11 +280,10 @@ function buildRequest(validBidRequests, bidderRequest, impressions, version) {
   // Since bidderRequestId are the same for different bid request, just use the first one.
   r.id = validBidRequests[0].bidderRequestId;
 
-  r.imp = impressions;
-
   r.site = {};
   r.ext = {};
   r.ext.source = 'prebid';
+  r.ext.ixdiag = {};
 
   // if an schain is provided, send it along
   if (validBidRequests[0].schain) {
@@ -358,30 +357,140 @@ function buildRequest(validBidRequests, bidderRequest, impressions, version) {
     if (typeof otherIxConfig.timeout === 'number') {
       payload.t = otherIxConfig.timeout;
     }
+
+    if (typeof otherIxConfig.detectMissingSizes === 'boolean') {
+      r.ext.ixdiag.dms = otherIxConfig.detectMissingSizes;
+    } else {
+      r.ext.ixdiag.dms = true;
+    }
   }
 
   // Use the siteId in the first bid request as the main siteId.
   payload.s = validBidRequests[0].params.siteId;
   payload.v = version;
-  payload.r = JSON.stringify(r);
   payload.ac = 'j';
   payload.sd = 1;
   if (version === VIDEO_ENDPOINT_VERSION) {
     payload.nf = 1;
   }
 
-  return {
+  const requests = [];
+
+  const request = {
     method: 'GET',
     url: baseUrl,
     data: payload
   };
+
+  const BASE_REQ_SIZE = new Blob([`${request.url}${utils.parseQueryStringParameters({...request.data, r: JSON.stringify(r)})}`]).size;
+  let currReqSize = BASE_REQ_SIZE;
+
+  const MAX_REQ_SIZE = 8000;
+  const MAX_REQ_LIMIT = 4;
+  let sn = 0;
+  let msi = 0;
+  let msd = 0;
+  r.ext.ixdiag.msd = 0;
+  r.ext.ixdiag.msi = 0;
+  r.imp = [];
+  let i = 0;
+  const transactionIds = Object.keys(impressions);
+  let currMissingImps = [];
+
+  while (i < transactionIds.length && requests.length < MAX_REQ_LIMIT) {
+    if (impressions[transactionIds[i]].hasOwnProperty('missingCount')) {
+      msd = impressions[transactionIds[i]].missingCount;
+    }
+
+    trimImpressions(impressions[transactionIds[i]], MAX_REQ_SIZE - BASE_REQ_SIZE);
+
+    if (impressions[transactionIds[i]].hasOwnProperty('missingImps')) {
+      msi = impressions[transactionIds[i]].missingImps.length;
+    }
+
+    let currImpsSize = new Blob([encodeURIComponent(JSON.stringify(impressions[transactionIds[i]]))]).size;
+    currReqSize += currImpsSize;
+    if (currReqSize < MAX_REQ_SIZE) {
+      // pushing ix configured sizes first
+      r.imp.push(...impressions[transactionIds[i]].ixImps);
+      // update msd msi
+      r.ext.ixdiag.msd += msd;
+      r.ext.ixdiag.msi += msi;
+
+      if (impressions[transactionIds[i]].hasOwnProperty('missingImps')) {
+        currMissingImps.push(...impressions[transactionIds[i]].missingImps);
+      }
+
+      i++;
+    } else {
+      // pushing missing sizes after configured ones
+      const clonedPayload = utils.deepClone(payload);
+
+      r.imp.push(...currMissingImps);
+      r.ext.ixdiag.sn = sn;
+      clonedPayload.sn = sn;
+      sn++;
+      clonedPayload.r = JSON.stringify(r);
+
+      requests.push({
+        method: 'GET',
+        url: baseUrl,
+        data: clonedPayload
+      });
+      currMissingImps = [];
+      currReqSize = BASE_REQ_SIZE;
+      r.imp = [];
+      msd = 0;
+      msi = 0;
+      r.ext.ixdiag.msd = 0;
+      r.ext.ixdiag.msi = 0;
+    }
+  }
+
+  if (currReqSize > BASE_REQ_SIZE && currReqSize < MAX_REQ_SIZE && requests.length < MAX_REQ_LIMIT) {
+    const clonedPayload = utils.deepClone(payload);
+    r.imp.push(...currMissingImps);
+
+    if (requests.length > 0) {
+      r.ext.ixdiag.sn = sn;
+      clonedPayload.sn = sn;
+    }
+    clonedPayload.r = JSON.stringify(r);
+
+    requests.push({
+      method: 'GET',
+      url: baseUrl,
+      data: clonedPayload
+    });
+  }
+
+  return requests;
 }
+/**
+ *
+ * @param {Object} impressions containing ixImps and possibly missingImps
+ *
+ */
+function trimImpressions(impressions, maxSize) {
+  let currSize = new Blob([encodeURIComponent(JSON.stringify(impressions))]).size;
+  if (currSize < maxSize) {
+    return;
+  }
 
+  while (currSize > maxSize) {
+    if (impressions.hasOwnProperty('missingImps') && impressions.missingImps.length > 0) {
+      impressions.missingImps.pop();
+    } else if (impressions.hasOwnProperty('ixImps') && impressions.ixImps.length > 0) {
+      impressions.ixImps.pop();
+    }
+    currSize = new Blob([encodeURIComponent(JSON.stringify(impressions))]).size;
+  }
+}
 /**
  *
  * @param  {array}   bannerSizeList list of banner sizes
  * @param  {array}   bannerSize the size to be removed
- * @return {boolean} true if succesfully removed, false if not found
+ * @return {boolean} true if successfully removed, false if not found
  */
 
 function removeFromSizes(bannerSizeList, bannerSize) {
@@ -496,19 +605,32 @@ export const spec = {
    */
   buildRequests: function (validBidRequests, bidderRequest) {
     let reqs = [];
-    let bannerImps = [];
-    let videoImps = [];
+    let bannerImps = {};
+    let videoImps = {};
     let validBidRequest = null;
 
     // To capture the missing sizes i.e not configured for ix
     let missingBannerSizes = {};
 
+    const DEFAULT_IX_CONFIG = {
+      detectMissingSizes: true,
+    };
+
+    const ixConfig = {...DEFAULT_IX_CONFIG, ...config.getConfig('ix')};
+
     for (let i = 0; i < validBidRequests.length; i++) {
       validBidRequest = validBidRequests[i];
 
       if (validBidRequest.mediaType === VIDEO || utils.deepAccess(validBidRequest, 'mediaTypes.video')) {
         if (validBidRequest.mediaType === VIDEO || includesSize(validBidRequest.mediaTypes.video.playerSize, validBidRequest.params.size)) {
-          videoImps.push(bidToVideoImp(validBidRequest));
+          if (!videoImps.hasOwnProperty(validBidRequest.transactionId)) {
+            videoImps[validBidRequest.transactionId] = {};
+          }
+          if (!videoImps[validBidRequest.transactionId].hasOwnProperty('ixImps')) {
+            videoImps[validBidRequest.transactionId].ixImps = [];
+          }
+
+          videoImps[validBidRequest.transactionId].ixImps.push(bidToVideoImp(validBidRequest));
         } else {
           utils.logError('Bid size is not included in video playerSize')
         }
@@ -516,27 +638,47 @@ export const spec = {
       if (validBidRequest.mediaType === BANNER || utils.deepAccess(validBidRequest, 'mediaTypes.banner') ||
           (!validBidRequest.mediaType && !validBidRequest.mediaTypes)) {
         let imp = bidToBannerImp(validBidRequest);
-        bannerImps.push(imp);
-        updateMissingSizes(validBidRequest, missingBannerSizes, imp);
+
+        if (!bannerImps.hasOwnProperty(validBidRequest.transactionId)) {
+          bannerImps[validBidRequest.transactionId] = {};
+        }
+        if (!bannerImps[validBidRequest.transactionId].hasOwnProperty('ixImps')) {
+          bannerImps[validBidRequest.transactionId].ixImps = []
+        }
+        bannerImps[validBidRequest.transactionId].ixImps.push(imp);
+        if (ixConfig.hasOwnProperty('detectMissingSizes') && ixConfig.detectMissingSizes) {
+          updateMissingSizes(validBidRequest, missingBannerSizes, imp);
+        }
       }
     }
-    // Finding the missing banner sizes ,and making impressions for them
-    for (var transactionID in missingBannerSizes) {
-      if (missingBannerSizes.hasOwnProperty(transactionID)) {
-        let missingSizes = missingBannerSizes[transactionID].missingSizes;
+
+    // Finding the missing banner sizes, and making impressions for them
+    for (var transactionId in missingBannerSizes) {
+      if (missingBannerSizes.hasOwnProperty(transactionId)) {
+        let missingSizes = missingBannerSizes[transactionId].missingSizes;
+
+        if (!bannerImps.hasOwnProperty(transactionId)) {
+          bannerImps[transactionId] = {};
+        }
+        if (!bannerImps[transactionId].hasOwnProperty('missingImps')) {
+          bannerImps[transactionId].missingImps = [];
+          bannerImps[transactionId].missingCount = 0;
+        }
+
+        let origImp = missingBannerSizes[transactionId].impression;
         for (let i = 0; i < missingSizes.length; i++) {
-          let origImp = missingBannerSizes[transactionID].impression;
           let newImp = createMissingBannerImp(origImp, missingSizes[i]);
-          bannerImps.push(newImp);
+          bannerImps[transactionId].missingImps.push(newImp);
+          bannerImps[transactionId].missingCount++;
         }
       }
     }
 
-    if (bannerImps.length > 0) {
-      reqs.push(buildRequest(validBidRequests, bidderRequest, bannerImps, BANNER_ENDPOINT_VERSION));
+    if (Object.keys(bannerImps).length > 0) {
+      reqs.push(...buildRequest(validBidRequests, bidderRequest, bannerImps, BANNER_ENDPOINT_VERSION));
     }
-    if (videoImps.length > 0) {
-      reqs.push(buildRequest(validBidRequests, bidderRequest, videoImps, VIDEO_ENDPOINT_VERSION));
+    if (Object.keys(videoImps).length > 0) {
+      reqs.push(...buildRequest(validBidRequests, bidderRequest, videoImps, VIDEO_ENDPOINT_VERSION));
     }
 
     return reqs;
diff --git a/modules/ixBidAdapter.md b/modules/ixBidAdapter.md
index b5cb0d9d2c1..c2e308870db 100644
--- a/modules/ixBidAdapter.md
+++ b/modules/ixBidAdapter.md
@@ -288,6 +288,26 @@ pbjs.setConfig({
     }
 });
 ```
+#### The **detectMissingSizes** feature
+With a recent update, the IX bid adapter bids on all banner sizes available in an ad unit, if IX is configured for at least one banner size in that ad unit. This default behavior if not required, can be turned off by using the `detectMissingSizes` flag.
+```
+pbjs.setConfig({
+                ix: {
+                    detectMissingSizes: false
+                }
+            });
+```
+OR
+```
+pbjs.setBidderConfig({
+                bidders: ["ix"],
+                config: {
+                    ix: {
+                        detectMissingSizes: false
+                    }
+                }
+            });
+```
 
 ### 2. Include `ixBidAdapter` in your build process
 
diff --git a/test/spec/modules/ixBidAdapter_spec.js b/test/spec/modules/ixBidAdapter_spec.js
index 63b04077f4e..ad4f90b0397 100644
--- a/test/spec/modules/ixBidAdapter_spec.js
+++ b/test/spec/modules/ixBidAdapter_spec.js
@@ -4,7 +4,7 @@ import { expect } from 'chai';
 import { newBidder } from 'src/adapters/bidderFactory.js';
 import { spec } from 'modules/ixBidAdapter.js';
 
-describe('IndexexchangeAdapter', function () {
+describe.only('IndexexchangeAdapter', function () {
   const IX_SECURE_ENDPOINT = 'https://htlb.casalemedia.com/cygnus';
   const VIDEO_ENDPOINT_VERSION = 8.1;
   const BANNER_ENDPOINT_VERSION = 7.2;
@@ -18,7 +18,6 @@ describe('IndexexchangeAdapter', function () {
         'sid': '00001',
         'hp': 1
       },
-
       {
         'asi': 'indirectseller-2.com',
         'sid': '00002',
@@ -26,7 +25,74 @@ describe('IndexexchangeAdapter', function () {
       }
     ]
   };
-
+  var div_many_sizes = [
+    [300, 250],
+    [600, 410],
+    [336, 280],
+    [400, 300],
+    [320, 50],
+    [360, 360],
+    [250, 250],
+    [320, 250],
+    [400, 250],
+    [387, 359],
+    [300, 50],
+    [372, 250],
+    [320, 320],
+    [412, 412],
+    [327, 272],
+    [312, 260],
+    [384, 320],
+    [335, 250],
+    [366, 305],
+    [374, 250],
+    [375, 375],
+    [272, 391],
+    [364, 303],
+    [414, 414],
+    [366, 375],
+    [272, 360],
+    [364, 373],
+    [366, 359],
+    [320, 100],
+    [360, 250],
+    [468, 60],
+    [480, 300],
+    [600, 400],
+    [600, 300],
+    [33, 28],
+    [40, 30],
+    [32, 5],
+    [36, 36],
+    [25, 25],
+    [320, 25],
+    [400, 25],
+    [387, 35],
+    [300, 5],
+    [372, 20],
+    [320, 32],
+    [412, 41],
+    [327, 27],
+    [312, 26],
+    [384, 32],
+    [335, 25],
+    [366, 30],
+    [374, 25],
+    [375, 37],
+    [272, 31],
+    [364, 303],
+    [414, 41],
+    [366, 35],
+    [272, 60],
+    [364, 73],
+    [366, 59],
+    [320, 10],
+    [360, 25],
+    [468, 6],
+    [480, 30],
+    [600, 40],
+    [600, 30]
+  ];
   const DEFAULT_BANNER_VALID_BID = [
     {
       bidder: 'ix',
@@ -587,7 +653,6 @@ describe('IndexexchangeAdapter', function () {
     it('IX adapter reads LiveRamp IDL envelope from Prebid and adds it to Video', function () {
       const cloneValidBid = utils.deepClone(DEFAULT_VIDEO_VALID_BID);
       cloneValidBid[0].userId = utils.deepClone(DEFAULT_USERID_DATA);
-
       const request = spec.buildRequests(cloneValidBid, DEFAULT_OPTION)[0];
       const payload = JSON.parse(request.data.r);
 
@@ -972,6 +1037,97 @@ describe('IndexexchangeAdapter', function () {
       expect(videoImp.video.h).to.equal(DEFAULT_VIDEO_VALID_BID[0].params.size[1]);
     });
 
+    it('single request under 8k size limit for large ad unit', function () {
+      const options = {};
+      const bid1 = utils.deepClone(DEFAULT_BANNER_VALID_BID[0]);
+      bid1.mediaTypes.banner.sizes = div_many_sizes;
+      const requests = spec.buildRequests([bid1], options);
+
+      const reqSize = new Blob([`${requests[0].url}?${utils.parseQueryStringParameters(requests[0].data)}`]).size;
+      expect(requests).to.be.an('array');
+      expect(requests).to.have.lengthOf(1);
+      expect(reqSize).to.be.lessThan(8000);
+    });
+
+    it('2 requests due to 2 ad units, one larger than url size', function () {
+      const bid1 = utils.deepClone(DEFAULT_BANNER_VALID_BID[0]);
+      bid1.mediaTypes.banner.sizes = div_many_sizes;
+      bid1.params.siteId = '124';
+      bid1.adUnitCode = 'div-gpt-1'
+      bid1.transactionId = '152e36d1-1241-4242-t35e-y1dv34d12315';
+      bid1.bidId = '2f6g5s5e';
+
+      const requests = spec.buildRequests([bid1, DEFAULT_BANNER_VALID_BID[0]], DEFAULT_OPTION);
+      expect(requests).to.be.an('array');
+      expect(requests).to.have.lengthOf(2);
+      expect(requests[0].data.sn).to.be.equal(0);
+      expect(requests[1].data.sn).to.be.equal(1);
+    });
+
+    it('6 ad units should generate only 4 requests', function () {
+      const bid1 = utils.deepClone(DEFAULT_BANNER_VALID_BID[0]);
+      bid1.mediaTypes.banner.sizes = div_many_sizes;
+      bid1.params.siteId = '121';
+      bid1.adUnitCode = 'div-gpt-1'
+      bid1.transactionId = 'tr1';
+      bid1.bidId = '2f6g5s5e';
+
+      const bid2 = utils.deepClone(bid1);
+      bid2.transactionId = 'tr2';
+
+      const bid3 = utils.deepClone(bid1);
+      bid3.transactionId = 'tr3';
+
+      const bid4 = utils.deepClone(bid1);
+      bid4.transactionId = 'tr4';
+
+      const bid5 = utils.deepClone(bid1);
+      bid5.transactionId = 'tr5';
+
+      const bid6 = utils.deepClone(bid1);
+      bid6.transactionId = 'tr6';
+
+      const requests = spec.buildRequests([bid1, bid2, bid3, bid4, bid5, bid6], DEFAULT_OPTION);
+
+      expect(requests).to.be.an('array');
+      expect(requests).to.have.lengthOf(4);
+
+      // check if seq number increases
+      for (var i = 0; i < requests.length; i++) {
+        const reqSize = new Blob([`${requests[i].url}?${utils.parseQueryStringParameters(requests[i].data)}`]).size;
+        expect(reqSize).to.be.lessThan(8000);
+        let payload = JSON.parse(requests[i].data.r);
+        if (requests.length > 1) {
+          expect(requests[i].data.sn).to.equal(i);
+        }
+        expect(payload.source.ext.schain).to.deep.equal(SAMPLE_SCHAIN);
+      }
+    });
+
+    it('multiple ad units in one request', function () {
+      const bid1 = utils.deepClone(DEFAULT_BANNER_VALID_BID[0]);
+      bid1.mediaTypes.banner.sizes = [[300, 250], [300, 600], [100, 200]];
+      bid1.params.siteId = '121';
+      bid1.adUnitCode = 'div-gpt-1'
+      bid1.transactionId = 'tr1';
+      bid1.bidId = '2f6g5s5e';
+
+      const bid2 = utils.deepClone(bid1);
+      bid2.transactionId = 'tr2';
+      bid2.mediaTypes.banner.sizes = [[220, 221], [222, 223], [300, 250]];
+      const bid3 = utils.deepClone(bid1);
+      bid3.transactionId = 'tr3';
+      bid3.mediaTypes.banner.sizes = [[330, 331], [332, 333], [300, 250]];
+
+      const requests = spec.buildRequests([bid1, bid2, bid3], DEFAULT_OPTION);
+      expect(requests).to.be.an('array');
+      expect(requests).to.have.lengthOf(1);
+
+      const impressions = JSON.parse(requests[0].data.r).imp;
+      expect(impressions).to.be.an('array');
+      expect(impressions).to.have.lengthOf(9);
+    });
+
     it('request should contain the extra banner ad sizes that IX is not configured for using the first site id in the ad unit', function () {
       const bid = utils.deepClone(DEFAULT_BANNER_VALID_BID[0]);
       bid.sizes.push([336, 280], [970, 90]);
@@ -1017,23 +1173,26 @@ describe('IndexexchangeAdapter', function () {
       const impressions = JSON.parse(request.data.r).imp;
       expect(impressions).to.be.an('array');
       expect(impressions).to.have.lengthOf(4);
-
-      expect(impressions[0].ext.siteID).to.equal(DEFAULT_BANNER_VALID_BID[0].params.siteId.toString())
-      expect(impressions[1].ext.siteID).to.equal(bid.params.siteId)
-      expect(impressions[2].ext.siteID).to.equal(DEFAULT_BANNER_VALID_BID[0].params.siteId.toString())
-      expect(impressions[3].ext.siteID).to.equal(bid.params.siteId)
+      expect(impressions[0].ext.siteID).to.equal(DEFAULT_BANNER_VALID_BID[0].params.siteId.toString());
+      expect(impressions[1].ext.siteID).to.equal(bid.params.siteId);
+      expect(impressions[2].ext.siteID).to.equal(DEFAULT_BANNER_VALID_BID[0].params.siteId.toString());
+      expect(impressions[3].ext.siteID).to.equal(bid.params.siteId);
 
       expect(impressions[0].banner.w).to.equal(DEFAULT_BANNER_VALID_BID[0].params.size[0]);
       expect(impressions[0].banner.h).to.equal(DEFAULT_BANNER_VALID_BID[0].params.size[1]);
+
       expect(impressions[1].banner.w).to.equal(bid.params.size[0]);
       expect(impressions[1].banner.h).to.equal(bid.params.size[1]);
+
       expect(impressions[2].banner.w).to.equal(DEFAULT_BANNER_VALID_BID[0].mediaTypes.banner.sizes[1][0]);
       expect(impressions[2].banner.h).to.equal(DEFAULT_BANNER_VALID_BID[0].mediaTypes.banner.sizes[1][1]);
+
       expect(impressions[3].banner.w).to.equal(bid.mediaTypes.banner.sizes[1][0]);
       expect(impressions[3].banner.h).to.equal(bid.mediaTypes.banner.sizes[1][1]);
 
       expect(impressions[0].ext.sid).to.equal(`${DEFAULT_BANNER_VALID_BID[0].params.size[0].toString()}x${DEFAULT_BANNER_VALID_BID[0].params.size[1].toString()}`);
       expect(impressions[1].ext.sid).to.equal(`${bid.params.size[0].toString()}x${bid.params.size[1].toString()}`);
+
       expect(impressions[2].ext.sid).to.equal(`${DEFAULT_BANNER_VALID_BID[0].mediaTypes.banner.sizes[1][0].toString()}x${DEFAULT_BANNER_VALID_BID[0].mediaTypes.banner.sizes[1][1].toString()}`);
       expect(impressions[3].ext.sid).to.equal(`${bid.mediaTypes.banner.sizes[1][0].toString()}x${bid.mediaTypes.banner.sizes[1][1].toString()}`);
     });
@@ -1045,6 +1204,28 @@ describe('IndexexchangeAdapter', function () {
       expect(impressions).to.be.an('array');
       expect(impressions).to.have.lengthOf(1);
     });
+
+    describe('detect missing sizes', function () {
+      beforeEach(function () {
+        config.setConfig({
+          ix: {
+            detectMissingSizes: false
+          }
+        });
+      })
+
+      it('request should not contain missing sizes if detectMissingSizes = false', function () {
+        const bid1 = utils.deepClone(DEFAULT_BANNER_VALID_BID[0]);
+        bid1.mediaTypes.banner.sizes = div_many_sizes;
+
+        const requests = spec.buildRequests([bid1, DEFAULT_BANNER_VALID_BID[0]], DEFAULT_OPTION);
+
+        const impressions = JSON.parse(requests[0].data.r).imp;
+
+        expect(impressions).to.be.an('array');
+        expect(impressions).to.have.lengthOf(2);
+      });
+    });
   });
 
   describe('buildRequestVideo', function () {