The retail media cage match: how Prime Day and Walmart+ squeeze ad budgets

How Prime Day became retail’s most expensive holiday

Amazon didn’t just launch a sale. It created its own shopping holiday and trained consumers to expect blockbuster deals every July. What began in 2015 as a one-day anniversary event to boost Prime memberships is now a fixture on the retail calendar.

Prime Day now runs 96 hours with themed ‘Big Deals’ to keep shoppers coming back each day. US online spending during Prime Day is forecast to hit $23.8bn, up 28% from the previous year’s $14.2bn over two days.

For Amazon, it’s a way to secure its position at the center of summer shopping, pull spending forward and lock in valuable first-party data. It’s also a crucial showcase for its $47bn advertising business, as brands compete for prime placements while shoppers are paying the most attention.

Walmart’s counter move and rising demands on brands

Walmart saw the threat early and began overlapping Prime Day with its own sales back in 2016. Today, Walmart+ Week runs exactly alongside Prime Day, featuring exclusive perks to keep Walmart+ members loyal.

It’s not just about matching deals. Walmart uses this period to strengthen Walmart Connect, its retail media business. It has asked brand partners to increase their retail media budgets by around 25% year over year to secure top placements during this critical sales period (Forbes).

Some reports say brands are increasing spend by as much as 50% to maintain preferred spots. Brands that hold back risk losing visibility in the app and online during the most competitive shopping week of the year.

At this point, it’s less of a seasonal sale and more of a competitive investment that brands plan for carefully each year.

The high-stakes squeeze for brands and advertisers

For advertisers, July’s sales window has become a required part of the marketing calendar. Skipping it can mean losing customers and valuable data to competitors willing to spend. But participating comes with higher costs, limited ad space and the need to manage parallel campaigns across both retail giants.

Advertising costs rise as brands bid for prime placement. Creative demands grow while margins shrink, all while shoppers expect strong discounts.

Even shopper enthusiasm has limits. Surveys show 84% still plan to shop during Prime Day, but average expected spend has dropped from around $300 to about $242. Stretching the event to four days can reduce urgency, leaving brands needing to sustain promotions and advertising for longer periods.

Amazon and Walmart control the digital shelves, the ad slots and the loyalty perks. For brands, staying visible during the summer’s biggest retail moment is very much a pay-to-play strategy: pay up or be pushed to the back of the shelf.