diff --git a/modules/appnexusAstBidAdapter.js b/modules/appnexusAstBidAdapter.js
index f3173dc15bc..890c69df243 100644
--- a/modules/appnexusAstBidAdapter.js
+++ b/modules/appnexusAstBidAdapter.js
@@ -1,11 +1,10 @@
 import { Renderer } from 'src/Renderer';
 import * as utils from 'src/utils';
 import { registerBidder } from 'src/adapters/bidderFactory';
-import { NATIVE, VIDEO } from 'src/mediaTypes';
+import { BANNER, NATIVE, VIDEO } from 'src/mediaTypes';
 
 const BIDDER_CODE = 'appnexusAst';
 const URL = '//ib.adnxs.com/ut/v3/prebid';
-const SUPPORTED_AD_TYPES = ['banner', 'video', 'native'];
 const VIDEO_TARGETING = ['id', 'mimes', 'minduration', 'maxduration',
   'startdelay', 'skippable', 'playback_method', 'frameworks'];
 const USER_PARAMS = ['age', 'external_uid', 'segments', 'gender', 'dnt', 'language'];
@@ -28,7 +27,7 @@ const SOURCE = 'pbjs';
 
 export const spec = {
   code: BIDDER_CODE,
-  supportedMediaTypes: [VIDEO, NATIVE],
+  supportedMediaTypes: [BANNER, VIDEO, NATIVE],
 
   /**
    * Determines whether or not the given bid request is valid.
@@ -100,7 +99,7 @@ export const spec = {
       serverResponse.tags.forEach(serverBid => {
         const rtbBid = getRtbBid(serverBid);
         if (rtbBid) {
-          if (rtbBid.cpm !== 0 && SUPPORTED_AD_TYPES.includes(rtbBid.ad_type)) {
+          if (rtbBid.cpm !== 0 && this.supportedMediaTypes.includes(rtbBid.ad_type)) {
             const bid = newBid(serverBid, rtbBid);
             bid.mediaType = parseMediaType(rtbBid);
             bids.push(bid);
@@ -206,9 +205,9 @@ function newBid(serverBid, rtbBid) {
       bid.adResponse.ad = bid.adResponse.ads[0];
       bid.adResponse.ad.video = bid.adResponse.ad.rtb.video;
     }
-  } else if (rtbBid.rtb['native']) {
-    const nativeAd = rtbBid.rtb['native'];
-    bid['native'] = {
+  } else if (rtbBid.rtb[NATIVE]) {
+    const nativeAd = rtbBid.rtb[NATIVE];
+    bid[NATIVE] = {
       title: nativeAd.title,
       body: nativeAd.desc,
       cta: nativeAd.ctatext,
@@ -241,6 +240,7 @@ function bidToTag(bid) {
   const tag = {};
   tag.sizes = transformSizes(bid.sizes);
   tag.primary_size = tag.sizes[0];
+  tag.ad_types = [];
   tag.uuid = bid.bidId;
   if (bid.params.placementId) {
     tag.id = parseInt(bid.params.placementId, 10);
@@ -279,19 +279,24 @@ function bidToTag(bid) {
     tag.keywords = getKeywords(bid.params.keywords);
   }
 
-  if (bid.mediaType === 'native' || utils.deepAccess(bid, 'mediaTypes.native')) {
-    tag.ad_types = ['native'];
+  if (bid.mediaType === NATIVE || utils.deepAccess(bid, 'mediaTypes.native')) {
+    tag.ad_types.push(NATIVE);
 
     if (bid.nativeParams) {
       const nativeRequest = buildNativeRequest(bid.nativeParams);
-      tag['native'] = {layouts: [nativeRequest]};
+      tag[NATIVE] = {layouts: [nativeRequest]};
     }
   }
 
   const videoMediaType = utils.deepAccess(bid, 'mediaTypes.video');
   const context = utils.deepAccess(bid, 'mediaTypes.video.context');
 
-  if (bid.mediaType === 'video' || (videoMediaType && context !== 'outstream')) {
+  if (bid.mediaType === VIDEO || videoMediaType) {
+    tag.ad_types.push(VIDEO);
+  }
+
+  // instream gets vastUrl, outstream gets vastXml
+  if (bid.mediaType === VIDEO || (videoMediaType && context !== 'outstream')) {
     tag.require_asset_url = true;
   }
 
@@ -303,6 +308,13 @@ function bidToTag(bid) {
       .forEach(param => tag.video[param] = bid.params.video[param]);
   }
 
+  if (
+    (utils.isEmpty(bid.mediaType) && utils.isEmpty(bid.mediaTypes)) ||
+    (bid.mediaType === BANNER || (bid.mediaTypes && bid.mediaTypes[BANNER]))
+  ) {
+    tag.ad_types.push(BANNER);
+  }
+
   return tag;
 }
 
@@ -399,12 +411,12 @@ function handleOutstreamRendererEvents(bid, id, eventName) {
 
 function parseMediaType(rtbBid) {
   const adType = rtbBid.ad_type;
-  if (adType === 'video') {
-    return 'video';
-  } else if (adType === 'native') {
-    return 'native';
+  if (adType === VIDEO) {
+    return VIDEO;
+  } else if (adType === NATIVE) {
+    return NATIVE;
   } else {
-    return 'banner';
+    return BANNER;
   }
 }
 
diff --git a/test/spec/modules/appnexusAstBidAdapter_spec.js b/test/spec/modules/appnexusAstBidAdapter_spec.js
index 3884b1c5863..af92aa40605 100644
--- a/test/spec/modules/appnexusAstBidAdapter_spec.js
+++ b/test/spec/modules/appnexusAstBidAdapter_spec.js
@@ -76,6 +76,30 @@ describe('AppNexusAdapter', () => {
       });
     });
 
+    it('should populate the ad_types array on all requests', () => {
+      ['banner', 'video', 'native'].forEach(type => {
+        const bidRequest = Object.assign({}, bidRequests[0]);
+        bidRequest.mediaTypes = {};
+        bidRequest.mediaTypes[type] = {};
+
+        const request = spec.buildRequests([bidRequest]);
+        const payload = JSON.parse(request.data);
+
+        expect(payload.tags[0].ad_types).to.deep.equal([type]);
+      });
+    });
+
+    it('should populate the ad_types array on outstream requests', () => {
+      const bidRequest = Object.assign({}, bidRequests[0]);
+      bidRequest.mediaTypes = {};
+      bidRequest.mediaTypes.video = {context: 'outstream'};
+
+      const request = spec.buildRequests([bidRequest]);
+      const payload = JSON.parse(request.data);
+
+      expect(payload.tags[0].ad_types).to.deep.equal(['video']);
+    });
+
     it('sends bid request to ENDPOINT via POST', () => {
       const request = spec.buildRequests(bidRequests);
       expect(request.url).to.equal(ENDPOINT);