Amazon still sits at the center of the U.S. marketplace economy, but sellers have more reasons than ever to look outside it.
Walmart is building a serious third-party marketplace around its retail network, fulfillment infrastructure and advertising business. eBay is growing again after years in which many sellers treated it as a secondary channel. Both companies are giving merchants another place to put inventory, advertising dollars and operational attention.
The right timing is also important. U.S. retail e-commerce sales reached an estimated $340.2 billion in the second quarter of 2026, up 12.2% from a year earlier. Online sales accounted for 17.1% of total U.S. retail sales during the quarter.
Amazon remains much larger than either rival. The change is happening somewhere else. Sellers no longer have to treat Amazon as the automatic home for every product, every advertising campaign and every fulfillment decision.
Walmart Is Giving Amazon Sellers Another Serious Option
Walmart spent years trying to turn Walmart.com into more than an online version of its stores. Marketplace growth in 2026 suggests that effort is gaining real momentum.
For merchants adding Walmart as another sales channel, logistics have become a major part of the decision. Walmart fulfillment services give sellers a way to store inventory inside the Walmart logistics network rather than handling every Marketplace order independently.
The company reported that Walmart U.S. Marketplace sales increased 52% year over year in the second quarter of fiscal 2027. Walmart U.S. e-commerce sales grew 24% during the same period, with Marketplace listed among the main contributors to that growth in the company Q2 FY27 results.
Fulfillment is increasingly connected to those marketplace numbers. Walmart said nearly half of its Marketplace business flowed through fulfillment services during the quarter.
Walmart also claims sellers using WFS record 50% higher GMV on average for products carrying the Fulfilled by Walmart tag with delivery promises of two days or less. The figure comes from Walmart first-party data, so sellers should treat it as platform-reported performance rather than a guaranteed result for every catalog.
The pitch extends beyond delivery speed. Walmart Marketplace currently charges no monthly setup or subscription fee. Sellers generally pay referral fees after a sale, and eligible merchants joining during the 2026 promotion period can receive referral fee discounts, fulfillment credits and advertising credits through its New-Seller Savings program.
Amazon sellers already know how quickly marketplace economics can change after storage, fulfillment, advertising and other operating costs enter the calculation. Walmart does not eliminate those expenses, but it gives merchants another set of numbers to run.
Walmart Is Still Much Smaller Than Amazon, but Growth Is Moving Faster
Scale remains the clearest difference between the two companies.
Marketplace Pulse estimates that Walmart has around 200,000 active Marketplace sellers in the United States and roughly $15 billion in third-party marketplace GMV. Amazon operates on a completely different level. Marketplace Pulse estimates Amazon U.S. third-party GMV at roughly $300 billion.
Yet smaller size also leaves Walmart with room to expand quickly. Marketplace Pulse reported that Walmart Marketplace recorded its fastest growth in years during 2026 as the retailer expanded assortment, delivery coverage and seller services.
Walmart also has an asset that most online marketplaces cannot copy. Thousands of physical stores already sit close to American households. Marketplace sellers can benefit from parts of that physical network, including customer returns at more than 4,600 U.S. Walmart locations.
Amazon built its advantage by making logistics part of the marketplace itself. Walmart is now applying a similar principle with a very different physical footprint behind it.
Walmart Wants Inventory That Sellers Previously Sent Somewhere Else
The competition becomes even more interesting when fulfillment moves outside Walmart.com.
Walmart Multichannel Solutions allows merchants to use Walmart infrastructure for orders generated on other channels. Walmart specifically lists Amazon, eBay, TikTok and independent ecommerce stores among the supported destinations.
A seller can therefore hold inventory inside the Walmart network even when the eventual customer never shops on Walmart.com.
That puts Walmart into competition with Amazon at two levels. One battle concerns where the sale happens. Another concerns which company stores, packs and ships the product.
For established sellers, the second contest may prove just as important as the first. Inventory placement influences delivery times, working capital, storage charges and the number of separate logistics systems a company must maintain.
eBay Is Growing Again Instead of Trying to Become Another Amazon
eBay presents a different challenge.
The company does not have to copy the Amazon fulfillment model to remain important to merchants. Its strength still comes from a massive marketplace with enormous listing depth, strong positions in specific product categories and an established international buyer base.
Recent numbers show renewed momentum. eBay reported $22.4 billion in GMV for Q2 2026, an increase of 15% year over year. U.S. GMV reached $11.7 billion, up 24%. Active buyers increased to 136 million from 134 million a year earlier.
The marketplace contained around 2.6 billion live listings at the end of the quarter.
Those numbers do not put eBay close to Amazon in total U.S. marketplace volume. They do show that sellers are dealing with a platform that is expanding rather than simply defending an aging customer base.
eBay Is Competing for Seller Visibility Budgets Too
Sellers do not allocate only inventory between marketplaces. They allocate advertising budgets as well.
eBay generated $570 million in first-party advertising revenue during Q2 2026. Its advertising system now includes general and priority Promoted Listings campaigns, store promotion and offsite advertising.
The company has also added AI-assisted seller tools. Its 2026 updates include AI listing features, automated dispute responses, advertising controls and product research tools available through Seller Hub.
Advertising is becoming particularly important because marketplace visibility is no longer purely organic. eBay changed its Promoted Listings system in January 2026 so priority campaigns receive exclusive eligibility for the first advertising position in search results. General campaigns remain available, but they no longer compete for that top sponsored slot.
That creates a dynamic Amazon merchants already know well. Joining a marketplace may be simple. Winning visibility after thousands of competing listings arrive can become expensive.
Amazon Still Has the Advantage Sellers Cannot Ignore
Competition from Walmart and eBay should not be confused with an Amazon collapse.
Amazon reported that third-party sellers accounted for 61% of worldwide paid units during Q2 2026. Revenue from third-party seller services reached $46.78 billion for the quarter, up 16% year over year excluding foreign exchange effects.
The company also says independent sellers generate more than 60% of sales in the Amazon store.
Amazon still offers something rivals have struggled to match at the same scale. A merchant can combine marketplace demand, Prime delivery, FBA, advertising, payment infrastructure and an enormous customer base inside one system.
Marketplace Pulse estimates Amazon generated about $830 billion in total worldwide GMV during 2025, including roughly $575 billion from third-party sellers. Sellers looking for volume cannot dismiss a marketplace of that size.
Amazon also keeps improving the machinery around its merchants. Sellers managing larger catalogs increasingly rely on software and automation, a shift covered in our guide to Amazon FBA and FBM seller automation tools.
Fees Are Giving Sellers a Reason to Compare Alternatives
Scale comes with a price.
Amazon charges Professional sellers $39.99 per month, plus referral fees that vary by category. FBA sellers can face fulfillment charges, monthly storage costs, aged inventory surcharges and other expenses connected to inventory handling.
For 2026, Amazon increased FBA fees by an average of eight cents per unit sold. Amazon said the change represented less than 0.5% of the price of an average item and added no new FBA fee categories. The company published the change in its 2026 U.S. referral and FBA fee update.
Eight cents alone is unlikely to push a profitable seller away from Amazon. The calculation changes when referral fees, fulfillment, storage, returns, advertising and inbound shipping costs all affect the same product margin.
Marketplace Pulse found that 49% of Amazon sellers surveyed for its 2026 Seller Index identified marketplace fees as a leading margin concern. Advertising spending followed closely at 46%.
Interestingly, frustration does not automatically lead to departure. The same research found many sellers were still increasing their Amazon business because customer demand remained too large to abandon.
Amazon, Walmart and eBay Are Fighting for Different Parts of the Same Seller
| Platform | Current Seller Attraction | Latest Relevant Signal |
| Amazon | Massive customer demand, FBA, Prime and mature advertising tools | Third-party sellers represented 61% of worldwide paid units in Q2 2026 |
| Walmart | Fast Marketplace growth, WFS, retail stores and no monthly Marketplace subscription fee | U.S. Marketplace sales increased 52% in Q2 FY27 |
| eBay | Large buyer base, huge listing catalog and strong seller tools for individual and specialized inventory | U.S. GMV increased 24% in Q2 2026 |
The important shift is not a mass migration from one marketplace to another.
More sellers are building operations capable of serving several marketplaces at once. Inventory software can synchronize stock. Advertising tools can measure performance by channel. Third-party logistics companies can prepare products for several platforms. Walmart can even fulfill orders generated by competing marketplaces.
Once that infrastructure exists, sellers can move individual products instead of moving an entire business.
The Marketplace War Is Becoming a Fight Over Seller Dependence
Amazon spent years becoming difficult for successful marketplace businesses to avoid. Walmart and eBay do not need to destroy that advantage to change seller behavior.
They only need merchants to become less dependent on it.
A brand that once generated 90% of marketplace revenue through Amazon might decide that 70% is enough. Another seller may send a group of high-margin products to Walmart, keep collectibles or used inventory on eBay and leave high-volume products inside FBA. Advertising budgets can move in the same way.
Each small shift matters because third-party marketplaces make money from more than the transaction itself. Fulfillment, storage, advertising, payments and seller services can all produce additional revenue after a merchant joins the platform.
Walmart clearly understands that model. eBay is expanding its advertising and seller technology around it. Amazon has already spent years proving how valuable the complete seller ecosystem can become.
Amazon Is Still the Giant, but Sellers Now Have More Leverage
No current data suggests that Walmart or eBay is close to overtaking Amazon as the dominant U.S. third-party marketplace.
The more meaningful change is happening inside seller businesses. Amazon is increasingly one major channel among several rather than the only marketplace worth serious investment.
Walmart has turned fulfillment, physical stores, faster delivery and aggressive Marketplace expansion into a credible alternative. eBay has returned to stronger GMV growth and continues improving the tools sellers use to advertise and manage inventory.
Amazon still offers unmatched marketplace scale, and many merchants will continue building around it. The difference in 2026 is that keeping all inventory, advertising spend and fulfillment capacity tied to a single platform looks less necessary than it once did.
The marketplace war therefore will not be decided only by which website attracts the most shoppers. The real contest is over which company gets the next product listing, the next pallet of inventory and the next dollar a seller decides to spend.
