diff --git a/lib/addons/prebid/analytics.md b/lib/addons/prebid/analytics.md
index 4023faa8..a791b8ad 100644
--- a/lib/addons/prebid/analytics.md
+++ b/lib/addons/prebid/analytics.md
@@ -130,5 +130,6 @@ Each sampled auction sends an `optable.prebid.auction` event with, among others:
 `bidderRequests` (with per-bid `status`, `cpm`, `size`, `splitTestAssignment`),
 `optableMatchers`, `optableSources`, `optableTargetingDone`, `liveintentEIDs`
 (with per-bidder `hasLiEids` and `liSources`), `bidWon`, `missed`,
+`adUnitCode` (first bid's ad unit), `totalBids` (received bids with a `cpm`),
 `url`, `tenant`, `prebidjsVersion`, `sessionDepth`, `pageAuctionsCount`,
 `originSlug`, and the parsed `userAgent`/`device`.
diff --git a/lib/addons/prebid/analytics.test.ts b/lib/addons/prebid/analytics.test.ts
index 09f8c63a..1989a1aa 100644
--- a/lib/addons/prebid/analytics.test.ts
+++ b/lib/addons/prebid/analytics.test.ts
@@ -194,7 +194,7 @@ describe("OptablePrebidAnalytics", () => {
 
       expect(result).toMatchObject({
         auctionId: "auction-123",
-        adUnitCode: "unknown",
+        adUnitCode: "ad-unit-1",
         totalRequests: 1,
         optableMatchers: ["matcher1"],
         optableSources: ["source1"],
@@ -1051,6 +1051,67 @@ describe("OptablePrebidAnalytics", () => {
       expect(payload.bidderRequests[0].status).toBe("RECEIVED");
     });
 
+    const bidCountAuction = (bidsPerRequest: (string | undefined)[][], bidsReceived: any[]) => ({
+      auctionId: "auction-bid-count",
+      bidderRequests: bidsPerRequest.map((adUnits, i) => ({
+        bidderCode: `bidder${i + 1}`,
+        bidderRequestId: `req-${i + 1}`,
+        ortb2: { site: { domain: "example.com" }, user: { eids: [] } },
+        bids: adUnits.map((adUnitCode, j) => ({ bidId: `bid-${i + 1}-${j + 1}`, adUnitCode })),
+      })),
+      bidsReceived,
+      noBids: [],
+      timeoutBids: [],
+    });
+
+    it("reports totalBids: 0 when no bids are received", async () => {
+      const payload = await analytics.toWitness(bidCountAuction([["ad-unit-1"], ["ad-unit-1"]], []), []);
+      expect(payload.totalBids).toBe(0);
+    });
+
+    it("reports totalBids: 1 for a single received bid", async () => {
+      const payload = await analytics.toWitness(
+        bidCountAuction([["ad-unit-1"], ["ad-unit-1"]], [{ requestId: "bid-2-1", cpm: 1.2 }]),
+        []
+      );
+      expect(payload.totalBids).toBe(1);
+    });
+
+    it("counts received bids with a cpm across bidder requests", async () => {
+      const payload = await analytics.toWitness(
+        bidCountAuction(
+          [
+            ["ad-unit-1", "ad-unit-2"],
+            ["ad-unit-1", "ad-unit-2"],
+          ],
+          [
+            { requestId: "bid-1-1", cpm: 1.2 },
+            { requestId: "bid-1-2", cpm: 0 },
+            { requestId: "bid-2-1", cpm: 0.8 },
+            { requestId: "bid-2-2", cpm: null },
+            { requestId: "bid-unrequested", cpm: 3 },
+          ]
+        ),
+        []
+      );
+      expect(payload.totalBids).toBe(3);
+    });
+
+    it("sets the top-level adUnitCode to the first bid's ad unit", async () => {
+      const payload = await analytics.toWitness(bidCountAuction([["ad-unit-1", "ad-unit-2"], ["ad-unit-3"]], []), []);
+      expect(payload.adUnitCode).toBe("ad-unit-1");
+    });
+
+    it("skips bids without an ad unit when setting the top-level adUnitCode", async () => {
+      const payload = await analytics.toWitness(bidCountAuction([[undefined], [undefined, "ad-unit-2"]], []), []);
+      expect(payload.adUnitCode).toBe("ad-unit-2");
+    });
+
+    it("falls back to an 'unknown' adUnitCode when there are no bids", async () => {
+      const payload = await analytics.toWitness(bidCountAuction([[], []], []), []);
+      expect(payload.adUnitCode).toBe("unknown");
+    });
+
     it("should extract splitTestAssignment from bidsReceived", async () => {
       const event = {
         auctionId: "auction-split-test",
diff --git a/lib/addons/prebid/analytics.ts b/lib/addons/prebid/analytics.ts
index 97f1b86f..31dac074 100644
--- a/lib/addons/prebid/analytics.ts
+++ b/lib/addons/prebid/analytics.ts
@@ -447,8 +447,10 @@ class OptablePrebidAnalytics {
 
     requests.forEach((request: any) => {
       request.bids.forEach((bid: any) => {
+        if (adUnitCode === "unknown" && bid.adUnitCode) adUnitCode = bid.adUnitCode;
         const bidReceived = bidsReceivedMap.get(bid.bidId);
         if (bidReceived) {
+          if (bidReceived.cpm != null) totalBids += 1;
           bid.status = STATUS.RECEIVED;
           bid.cpm = bidReceived.cpm;
           bid.size = `${bidReceived.width}x${bidReceived.height}`;
@@ -479,6 +481,7 @@ class OptablePrebidAnalytics {
       auctionId,
       adUnitCode,
       totalRequests: bidderRequests.length,
+      totalBids,
       optableSampling: this.config.samplingRate || 1,
       // Processor schema declares optableTargetingDone as STRING and checks IN ('1','true').
       // Send '1'/'0' so Spark reads a predictable string regardless of matcher count.