The Numerator Data Says Walmart Is Losing Grocery Share. We Say Not So Fast.

Numerator’s latest panel data shows Walmart’s U.S. grocery share at 19.9%, down from 20.0% in 2025 and 20.4% in 2024. Costco moved up to 8.2% from 7.6% two years prior. Kroger fell to 8.3% from 8.8%. On Numerator’s broader CPG measure, Walmart sits at 20.4%, down from 21.1% in 2024, with Amazon and Whole Foods combined climbing to 8% from 6.4%. Supermarket News framed the trend last week by asking whether Walmart should be scared, treating the numbers as a coherent signal that the largest grocer in the country is in trouble.

The conclusion does not survive a closer read.

A Decimal Point Is Not a Trend Until You Know What’s Underneath It

Numerator’s share figures come from its consumer panel of more than a million U.S. households, anchored in receipt capture and digital account connections. The company has been explicit that this approach was built specifically to see the roughly 55% of shopping that traditional point-of-sale aggregation misses, including eCommerce, club, and channels where retailers do not contribute POS data. That is the right tool for measuring omnichannel reality.

A retailer’s share of a category can fall while its dollar sales rise, provided the category grows faster than the retailer. That is the situation here. The Census Bureau’s March 2026 advance retail trade report shows total U.S. retail and food services sales up 4.0% year over year. Walmart’s Q4 FY26 earnings release, filed February 19, reports U.S. comp sales up 4.6%, eCommerce up 27%, and grocery comps up mid single-digits, with broad-based share gains across income tiers led by upper-income households. Walmart’s own register data, audited and filed with the SEC, shows grocery growing and Walmart taking share. Numerator’s panel data, measured across a different timeframe and a broader definition of channels, shows Walmart’s share of total consumer grocery spend ticking down 0.1 point year over year. Both are accurate. Only one of them produced a headline.

The Share Gainers Aren’t Taking Walmart’s Trips

Costco reported U.S. comparable sales up 5.9% (6.4% adjusted) in its Q2 fiscal 2026 quarter ended February 15, with digitally-enabled comp sales up 22.6%. Costco’s food categories have been growing faster than the warehouse segment overall for several quarters. The shopper buying more food at Costco is not a Walmart shopper switching wholesale to a different format. Costco and Walmart serve overlapping but structurally distinct trips: Costco for the bulk run on a membership basis, Walmart for the weekly stock-up and fill-in on no membership at all. A household that adds a Costco run rarely stops going to Walmart. It compresses the supermarket trip in between.

Amazon and Whole Foods are the more interesting case. Their combined Numerator CPG share rose 1.6 percentage points over two years, the largest move in the top five. That growth correlates directly with the same upper-income, digital-first grocery shopper Walmart is competing for. On Walmart’s Q4 FY26 call, the company attributed the majority of share gains to households earning more than $100,000, a pattern reported for several consecutive quarters. The eCommerce mix reached a record 23% of U.S. sales for the quarter, with store-fulfilled delivery up roughly 50% and Walmart Connect up 41%. The digital grocery shopper is not making a binary choice between Walmart and Amazon. They are buying from both, and both are pulling share out of the same place.

That place is the conventional supermarket channel. Kroger’s 0.5-point Numerator grocery decline and Albertsons’ 0.3-point grocery decline are the structurally consequential numbers in the same dataset. They describe a real shift in where the American grocery dollar is going. Walmart’s 0.5-point three-year drift, set against grocery dollar growth in its own filings, describes something smaller: a market leader holding most of its position while two faster-growing channels eat the conventional middle.

The Supplier Misallocation Hidden in the Headline

A 1P supplier reading “Walmart is losing grocery” as a reason to hedge spend, concede endcap real estate, or redirect innovation to a competitor is reading against the grain of where the grocery basket is actually consolidating. Walmart’s grocery business is growing in dollars, its shopper mix is shifting toward higher-spending households, and its private brand is being repositioned to compete in segments where national brands have historically been safe. Walmart’s announced overhaul of Great Value, beginning with salty snacks in May 2026 before extending to dairy and cereal, is calibrated to the upper-income shopper the retailer is now winning. Suppliers whose value proposition is anchored only against a price-sensitive lower-income customer are exposed. The exposure is not because Walmart is shrinking. It is because Walmart’s customer is changing faster than the supplier’s positioning is.

The implications for 3P Marketplace sellers are real but smaller in this specific argument, because Numerator’s grocery and CPG share readings are predominantly a 1P story. Where 3P sellers should pay attention is the eCommerce flywheel underneath the share data. Marketplace sales were up roughly 20% in Q4 FY26, with Walmart Fulfillment Services utilization at a record 52%. The digital growth pulling upper-income grocery baskets onto Walmart.com is the same digital growth feeding pantry-adjacent, kitchen, and wellness Marketplace categories. Connect budgets and listing strategies calibrated to an older assumption about the Walmart.com shopper are competing for the wrong click.

The Read That Holds Up

Numerator’s panel is doing what it was built to do: measure omnichannel consumer spending without depending on retailer cooperation. The story the data is telling, read carefully, is that the conventional supermarket channel is losing ground to club and digital, with Walmart caught in that shift but holding most of its position by growing into the same higher-income, digital-first basket Costco and Amazon are also competing for. A supplier who treats a 0.1-point panel decline as a reason to retreat from a retailer posting mid single-digit grocery comps, 27% eCommerce growth, and 41% Connect growth is reorganizing around the headline at the expense of the business that headline misrepresents.

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