Prime Big Deal Days ran on October 6 and 7, and the first proper read on ad performance is in. The short version: sellers more than doubled their Amazon ad budgets, clicks got only slightly more expensive, and conversion rate did almost all of the work. The less comfortable finding is that the second day gave back most of the efficiency gain.
Adobe put total US online spend across the two days at $9.86 billion, up 8.5% year over year, with discounts peaking at 20% off list price. Demand turned up. The question for advertisers is what it cost to capture it.
What the Ad Data Shows
Triple Whale published benchmarks from roughly 1,900 brands and 2,100 Amazon ad accounts, comparing the event with the seven days before it. Four things stand out.
1. Budgets More Than Doubled
Average daily Amazon ad spend across the sample rose 148.7%, from $3.50 million a day in the prior week to $8.70 million a day during the event. Platform-reported purchases rose 183.4% per day, so orders grew faster than spend.
2. Clicks Cost About 6% More
Median CPC moved from $1.44 to $1.52, a 5.9% increase. CPM was up just 1.5%. For an event where sellers habitually brace for a bidding war, that is a mild rise.
3. Conversion Rate Did the Heavy Lifting
Median conversion rate climbed from 9.96% to 11.77%, an 18.2% lift and the only metric that moved by more than 10%. Click-through rate actually fell 6.1%. Shoppers were not clicking more ads. The ones who clicked were far more ready to buy.
4. Baskets Got Smaller
Median ROAS improved from 2.94x to 3.11x and CPA fell 7.5%, but average order value dropped 5.1% to $37.91. A better ROAS on a discounted price is not automatically a better profit.
Day Two Was the Weak Link
The two-day averages hide a sharp split:
- October 6: ROAS 3.34, CPA $12.81, CPC $1.48, conversion rate 12.13%
- October 7: ROAS 2.90, CPA $14.68, CPC $1.57, conversion rate 11.30%
ROAS fell 13.2% from day one to day two and CPA rose 14.6%. Brands trimmed spend by 9.5% on the second day, but purchases fell 24.4%. Day-two ROAS of 2.90 sat below the 2.94 median from the ordinary week before the event.
In other words, the event premium was earned almost entirely on the first day. On the second, sellers were paying the highest CPCs of the fortnight for returns no better than a normal Tuesday.
Not Every Category Won
Category results varied widely against the prior week:
- Sports and outdoors: ROAS up about 27%, CPA down 23%
- Consumer electronics: ROAS up 16.3%, CPA flat
- Home and garden: ROAS up 13%, CPA down 13%
- Baby: spend up 240.5%, ROAS up only 5.7%, CPM up 13.4%
- Food and beverage: spend up 135%, ROAS down 1.5%
- Pets: spend up 115.2%, ROAS down 0.4%
- Automotive: spend up 65.9%, ROAS down 9.5%
The winners were giftable, higher-ticket categories where shoppers wait for a price drop. Consumables and replenishment categories doubled their budgets and got roughly the same return they would have had anyway.
Important note: these are platform-reported medians from brands using one analytics tool, and health and beauty made up 49.3% of the Amazon spend in the sample. Treat them as a direction of travel, not a target for your own account.
What to Do Before Black Friday
Black Friday and Cyber Monday are about six weeks out. The October event is the closest rehearsal you will get, so use it.
- Split your own event data by day. Pull October 6 and October 7 separately for spend, CPC, conversion rate and ROAS. If your second day looked like the benchmark, plan a front-loaded budget for the next event instead of an even split.
- Recalculate ROAS on the discounted price. Take your event ROAS and check it against break-even after the deal discount, Amazon fees and returns. A 3.1x ROAS on a 20% discount can be worse than a 2.9x at full price.
- Find where the conversion lift came from. List the campaigns and ASINs whose conversion rate jumped during the event. Those are the ones that justify higher bids in November. Anything that converted at its normal rate does not need an event budget.
- Be honest about your category. If you sell consumables, pet supplies or automotive parts, the data says doubling spend bought very little. Hold budgets closer to baseline and protect margin.
- Set day-level budget rules now. Schedule budget increases for the opening day of each event and a step down after it, so pacing does not depend on someone checking the account mid-sale.
The Takeaway
Prime Big Deal Days 2026 was not a CPC bloodbath. It was a conversion event, concentrated in the first 24 hours and in a handful of categories. Sellers who spent the same on both days paid for that assumption. Check your own day-one and day-two numbers this week, and build the Black Friday plan around what they show.
