Amazon Just Overtook Walmart as the Country's Biggest Retailer: What the Power Shift Means for Where You Sell

One reason Amazon's GMV has grown so dramatically is its third-party marketplace.

Marketplace Pulse estimates that Amazon generated $830 billion in GMV in 2025, including approximately $575 billion from third-party marketplace sales. That means independent sellers are responsible for a huge portion of the transactions happening across Amazon's ecosystem.

That changes the equation for brands.

Amazon isn't simply a retailer where you hand over inventory and wait for sales. It is an entire commerce ecosystem involving advertising, fulfillment, marketplace infrastructure, seller services, reviews, search, data and increasingly AI-powered product discovery.

For brands operating an Amazon 3P Accelerator strategy, that scale creates an enormous opportunity. But it also means competition is becoming harder to ignore.

More sellers are fighting for the same customer attention. Advertising gets more sophisticated. Pricing becomes more competitive. And a strong product alone isn't enough to guarantee visibility.

Your listings, inventory, advertising, pricing and customer experience all have to work together.

This is where things get interesting.

Amazon's rise doesn't mean Walmart has suddenly become irrelevant. In fact, Walmart's marketplace is growing at a pace that sellers should pay attention to.

Marketplace Pulse reported that Walmart's U.S. third-party marketplace grew nearly 50% year over year in the first quarter of fiscal 2027, its fastest growth in years.

That's a very different opportunity from Amazon.

Amazon gives sellers enormous scale, but Walmart can offer access to a marketplace that is still comparatively less mature. Marketplace Pulse estimated Walmart's marketplace GMV at around $15 billion, compared with Amazon's much larger marketplace business.

For a seller, that creates an interesting Q4 question:

Do you want to keep putting every growth dollar into the biggest marketplace, or start building a meaningful second channel before everyone else does?

Q4 has a way of exposing weak channel strategies.

A brand might have excellent Amazon sales but discover that rising ad costs are eating into margins. Another might have strong Walmart demand but insufficient inventory. A third might depend almost entirely on one marketplace's algorithm.

That's why Marketplace Management Services become more important as brands expand across channels.

Managing multiple marketplaces isn't simply copying an Amazon listing onto Walmart. Each platform has different shoppers, search behavior, promotional tools, fulfillment options and advertising systems.

The goal should be to understand what each channel does best and assign the right role to it.

Amazon might remain your primary scale engine.

Walmart could become your diversification play.

And other channels such as TikTok Shop, Shopify or additional marketplaces can support discovery, direct relationships or specific product categories.

A Global Ecommerce Accelerator approach makes this easier because the objective isn't to choose one marketplace and ignore everything else. It is to build a coordinated channel strategy around where customers actually shop.

If your brand is heavily concentrated on Amazon, this is a good moment to look beyond your current sales dashboard.

Start by asking three questions.

First: Where are we already seeing demand outside Amazon?

Look at website traffic, marketplace searches, customer requests and category performance. You may already have evidence pointing toward your next channel.

Second: Can our operations support another marketplace?

Expanding to Walmart sounds simple until you consider inventory synchronization, fulfillment, catalog management, pricing, customer service and reporting. Your backend needs to be ready before the listings go live.

Third: What role should each channel play?

Don't expect every marketplace to perform exactly the same way. Amazon may drive the largest sales volume, while Walmart provides incremental reach. Your DTC site may deliver stronger customer ownership, while social commerce may generate product discovery.

That's where a Global Ecommerce Accelerator can help turn multiple channels into one coordinated growth strategy rather than a collection of disconnected storefronts.

The Amazon-Walmart race is easy to turn into a headline.

For sellers, the more useful takeaway is different.

You don't need to pick a winner. You need to build a business that can win on more than one channel.

Amazon's enormous GMV proves how powerful the marketplace has become.

Walmart's marketplace growth shows there is still room for another major player to gain ground.

And as Q4 approaches, brands that have already invested in Amazon 3P Accelerator capabilities and Marketplace Management Services can focus less on reacting to individual marketplace changes and more on deciding where the next dollar of inventory, advertising and operational investment should go.

A strong Global Ecommerce Accelerator strategy starts with exactly that question:

Where will your next customer come from, and is your brand ready to meet them there?