Costco’s grocery market share reached 8.3% at the end of June, up from 7.9% a year earlier and 7.6% in mid-2024, while the club retailer’s fresh comparable-store sales rose in the mid-single digits in the quarter that followed its third-quarter earnings. Traditional grocers over the same period reported comparable sales that were slower or negative, according to Numerator and company disclosures.
The membership model keeps paying off
The share gains came despite the friction of a paid membership requirement. YouGov data showed U.S. consumers, particularly younger ones, now rate Costco above Aldi on value perception. The discounter has long been the benchmark for price image; Costco’s overtaking it suggests the warehouse format is no longer a niche but a mainstream destination for weekly food shopping.
Fresh categories drive the gap
Bakery and meat departments led Costco’s fresh comp acceleration. The company attributed part of its third-quarter strength to protein-focused private-label items aimed at consumers using GLP-1 medications, a product development cycle that traditional supermarkets have been slower to match. While Walmart, Amazon, Aldi and dollar chains have been the recognized competitive set for years, the data now puts the club operator at the center of the threat matrix.
Promotions elsewhere look incremental
Amazon’s Prime Day, running October 6-7, will feature organic Honeycrisp apples at $2 per two-pound bag, ground beef and Dietz and Watson Genoa salami under $3, and a slate of $1 deals on Sabra hummus and cherry tomatoes. Last year’s June event saw grocery participation drop to a four-year low of 16% of Prime shoppers. Meijer added two Midwest locations this week, a 75,000-square-foot Meijer Grocery in Fishers, Indiana, and a 159,000-square-foot supercenter in Plymouth Township, Michigan, expanding a regional footprint that now includes six grocery-format stores and 130 supercenters in its home state. Aldi plans to relaunch its oversized “Big Bag” tote on October 14 after a prior sellout of 45,000 units in minutes, followed by pickle-flavored and “girl dinner”-inspired pizzas under the Mama Cozzi’s label.
What to watch next
The next quarterly reports from Kroger, Albertsons and Ahold Delhaize will show whether the comp gap narrows or widens. Costco’s renewal rate and any membership fee increase, the last was in 2023, will signal how much pricing power the model carries. Meanwhile, the promotional calendar is crowded: Amazon’s fall Prime Day, Aldi’s limited-time drops, and regional expansions from Meijer and others. The club retailer does not run weekly circulars. Its share gain suggests it may not need to.