Overview

Amazon is advising sellers to use the “down only” dynamic bidding option for Sponsored Products campaigns that target the back‑to‑school shopping window. Internal performance data shows that this conservative bidding mode delivers a measurable lift in return on ad spend (ROAS) for newly launched ASINs compared with the more aggressive “up and down” approach. Sellers in school‑supply categories should consider the recommendation to protect budgets while the season drives higher cost‑per‑click rates.

Key Points

• Dynamic “down only” endorsed — Amazon officially recommends the “down only” strategy for new ASINs launched during the back‑to‑school period.
• 18% higher ROAS — Advertisers who used “down only” saw an average 18 % increase in return on ad spend versus “up and down” bidding.
• 7.4% more clicks — Campaigns with the conservative mode generated 7.4 % additional clicks on average.
• 6.2% more orders — The same campaigns recorded a 6.2 % rise in ad‑attributed orders.
• Three bidding choices — Sponsored Products offers fixed bids, dynamic “down only,” and dynamic “up and down” as selectable options.

How Down Only Bidding Works

1. Bid ceiling set by seller — The advertiser defines a maximum cost‑per‑click (CPC) for each keyword or product target. For example, a seller may set a $1.20 ceiling for “math notebook.”
2. Algorithm reduces bids in real time — When Amazon’s system predicts a low probability of conversion—such as a query “used school supplies” or a placement on the second page of search—it automatically lowers the bid below the seller‑defined maximum. In the example, the bid might drop to $0.70 for that impression.
3. Bid never exceeds the ceiling — Unlike the “up and down” mode, the algorithm does not raise the bid above the set limit, ensuring spend never surpasses the seller’s budget cap even during high‑traffic moments.

Context: Before vs. After

• Before: A seller launching a new “ergonomic pencil case” during August used the default “up and down” bidding. The algorithm frequently increased bids on marginal placements, leading to CPC spikes above $1.50 and rapid budget depletion without sufficient sales data to justify the spend.