For thirteen years the title of America's largest retailer belonged to Walmart, and the assumption that it always would was baked into how the industry thinks about itself. That era is over. In a client note circulating this week, J.P. Morgan's retail team led by analyst Doug Anmuth concluded that Amazon overtook Walmart as the largest U.S. retailer by gross merchandise value at some point in 2025 — and the lead is widening, as PYMNTS reported.

The supporting numbers are the part worth sitting with. Amazon's share of U.S. consumer retail spending reached 9.3% in the first quarter of 2026, up from 8.6% a year earlier. Walmart's share held at 7.8% — exactly where it sat in the first quarter of 2025. One company is compounding; the other is holding serve. J.P. Morgan now pegs Amazon at roughly 47% of the U.S. e-commerce market and says its retail business outgrew the broader online channel last quarter. Amazon already leads in four of seven major retail categories, including electronics and appliances, furniture and home furnishings, apparel, and the sporting-goods-hobby-books cluster.

This was the metric, not a surprise

None of this came out of nowhere. Earlier this year Amazon passed Walmart on the measure that makes headlines — total company revenue — topping the Fortune 500 and ending Walmart's 13-year run at No. 1. It also surpassed Walmart in quarterly revenue for the first time, a milestone CNN framed as the moment retail's center of gravity formally shifted from Bentonville to Seattle. But those comparisons are muddied — Amazon's top line is inflated by AWS and a fast-growing ad business, while Walmart's is overwhelmingly low-margin groceries. The J.P. Morgan note matters precisely because it strips the conglomerate noise out and measures the thing both companies actually fight over: goods sold to American shoppers.

The yardstick is doing real work

There's a catch worth being honest about. Gross merchandise value counts the full price of everything sold across a platform — including the third-party marketplace sellers who account for the majority of Amazon's units and whose sales Amazon never books as its own revenue. By that measure Amazon looks enormous; by net retail revenue or U.S. store sales, Walmart remains a colossus and still owns the single most valuable franchise in American retail, the weekly grocery run.

So which number is "right"? Increasingly, GMV is. It is the metric that governs how much leverage a retailer has over suppliers, how large its retail-media ad pool can grow, and how many third-party merchants build their businesses on the platform. Walmart understands this — it is the reason Walmart Marketplace, Walmart Connect advertising, and its third-party fulfillment push are the company's most strategically important investments, not its stores. The shift J.P. Morgan is measuring is the same one Walmart's own roadmap concedes: the future profit pool sits in the marketplace-and-media flywheel Amazon built first.

What it means for everyone downstream

For brands and suppliers, the takeaway is uncomfortable but clarifying: the platform that now moves the most product in America is the one where you are simultaneously a vendor, an advertiser, and a competitor against Amazon's own private labels. For Walmart, holding share flat in a growing market is not failure, but it is a warning — the company has to convert its grocery dominance and store footprint into the kind of online frequency that compounds, and it has to do it while Amazon's lead in higher-margin categories widens.

As Endcap noted when Amazon yanked Prime Day forward into June and forced every rival to counter-program around it, the tell isn't any single move — it's that the rest of retail now reacts to Amazon's clock. Wall Street just put a number on what that clock has already done. America has a new largest retailer, and the only real debate left is how far ahead it gets before anyone catches up.