Your Sponsored Products campaign overspending by 40% on Black Friday, despite having a daily budget cap, is likely due to Amazon's flexible budget system, not a platform bug or policy violation.
Why It Happens:
Amazon allows campaigns to exceed the daily budget by up to 25% to accommodate high-traffic fluctuations, especially during events like Black Friday or Cyber Monday.
According to Amazon’s official documentation:
“Campaigns may exceed the daily budget by up to 25% on a given day, as long as the monthly spend does not exceed the average daily budget times the number of days in the month.”
However, during major retail events, there are two key reasons why you may see even greater variance:
Intra-day Budget Recalibration: Amazon dynamically allocates spend to hours of high opportunity. If click volume surges early in the day, the system may accelerate spend aggressively.
Budget Smoothing Across Days: Amazon balances overspend on some days by underspending on others—as long as the monthly average stays within bounds. If your campaign underspent earlier in the month, it may "borrow" unused budget to capitalize on Black Friday traffic.
What You Can Do:
Check campaign delivery and billing reports to compare daily vs. average monthly spend.
Use Budget Rules to better control daily limits during event spikes.
Consider setting strict portfolio caps or use campaign-level pacing tools if you need tighter control.
Amazon doesn’t ignore your budget—but it may temporarily exceed it for performance optimization, especially during high-traffic sales periods.