Prime Day 2025 was once again a blockbuster for brands on Amazon. Across the board, ordered product sales (OPS) rose 18.6% compared to 2024, reinforcing the pull of this yearly shopping event. Traffic climbed 10%, while conversion rates improved by 2.2%, demonstrating that shoppers weren’t just browsing, they were buying.

While many brands saw sales increases, a few significantly outperformed the rest. The difference was how these brands leveraged agentic AI to adjust their bids throughout the event, capturing additional sales and gaining market share from competitors.

A new Prime Day shopping experience

This year, Amazon expanded Prime Day to four days, changing the dynamics of shopping activity. On Day 1, sales peaked at 376% above baseline compared to 544% last year. But a slower start didn’t mean customers weren’t shopping — they were strategizing. They now had time to plan their purchases, rather than frantically scrambling to check out within 48 hours. By Day 4, sales surged again, and total ordered revenue rose sharply year-over-year. 

Just as customers rethink how they buy during these significant sales events, brands must also adapt their selling approach.

The widening performance gap

High-traffic events like Prime Day are rare moments when consumer intent spikes across categories. They offer brands a chance to capture sales and magnify the challenge of standing out in a crowded, competitive field.

Even before Prime Day 2025, brands were ramping up their fight for share of voice and digital shelf presence. Once the event began, ad spend jumped 283%. But the brands that did well weren’t just spending more; they were spending smarter. 

Their winning strategy was built on intraday media purchasing, which dynamically adjusts bids and budgets based on real-time signals like demand shifts, competitor moves, and inventory status. It applies the classic investment mantra “buy low, sell high” to retail media. Bid aggressively when opportunity outweighs competition, and pull back when bids become inefficient. 

Rather than chasing an immediate return on ad spend, these brands focused on driving incremental sales throughout the event, making every second count.

Optimizing for every opportunity 

Retail media success is typically measured by surface-level KPIs like click-through rates, ROAS, and attributed sales. But these metrics often mask the truth. A high ROAS can be misleading if much of the attributed sales would have happened anyway.

Incrementality changes the conversation. It isolates the net-new sales driven by advertising, the purchases that wouldn’t have happened without the campaign. 

Traditionally, incrementality measurement has been post-mortem, comparing control and holdout groups after the fact. But AI enables lightning-fast, in-flight calculations that guide live bidding decisions. It allows brands to instantly evaluate which keyword investments will generate true incremental value, thereby avoiding wasted spend that cannibalizes organic sales.

At the heart of these Prime Day wins is the adoption of agentic AI to optimize bid and budget performance across:

• Impressions and click-through rates
• Share of voice metrics
• SKU- and keyword-level attributes
• Inventory status and Buy Box ownership
• Competitive pressure indicators
• Propensity-to-convert scores

Using a brand’s goal values, budget pacing, and campaign plan, agentic AI sets optimal bids for every keyword daily and recalculates throughout the day as conditions change. One of its core capabilities is finding the precise bid that maximizes returns without overspending or missing opportunities. Unlike static bid rules, this model is brand-specific, retrained daily, and weighted toward the most recent data, ensuring strategies adapt instantly to evolving market dynamics.

The system operates at the target level, not just the campaign level. That means every bid is tuned to generate incremental results, not just meet average portfolio efficiency.

Winning future sales events

The lesson from Prime Day 2025 is clear: As sales events stretch longer and competition intensifies, optimization must evolve from static planning to real-time, incrementality-focused execution.

For CPG marketers, that means:

1. Adopting AI-driven decision-making to capture real-time opportunities invisible to manual optimization.
2. Focusing on incrementality rather than inflated ROAS metrics.
3. Operating at the keyword level for precision bidding.
4. Retraining models daily to adapt to fast-changing conditions.

The 2025 Prime Day winners weren’t outliers. They were the predictable outcome of a system designed to challenge conventional KPIs and prioritize driving net-new growth. Top performers didn’t simply buy more media than the other competitors in their category — they identified and captured the highest-opportunity keywords at precisely the right time.

By making incrementality a core part of campaign optimization, these brands created a blueprint for navigating the future of retail media. In the next big shopping event, whether it’s Black Friday, Cyber Monday, or next year’s Prime Day, the leaders won’t just be the brands with the biggest budgets. They’ll be the brands with the smartest bids.

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