How the rotation works
Multiple eligible sellers can share the Buy Box on the same listing. The algorithm rotates between them based on price, fulfillment speed, seller performance metrics (defect rate, late shipment rate, cancellation rate), and inventory availability. FBA sellers win against merchant-fulfilled sellers roughly 85–90% of the time at similar prices. Your Buy Box percentage tells you what share of the rotation you're winning.
The strategic angle most brands miss
Buy Box loss is treated as a tactical pricing issue. It's actually a JBP credibility issue. If you're the brand owner and unauthorized sellers keep winning the Buy Box on your own listings, your retail media spend funnels traffic to a third-party seller selling at a different price — and the JBP commitment you negotiated with Amazon means very little if your own catalog isn't pricing-clean. The fix sits at the intersection of Brand Registry enforcement, MAP discipline, and authorized-seller program design.