An H-E-B employee loads groceries into a customer’s car at a store.

H-E-B narrowly bested Amazon and its Amazon Fresh subsidiary — as well as its chief rival, Walmart — as the top U.S. online grocer in a new study from dunnhumby.

The U.K.-based customer data science firm said San Antonio-based H-E-B edged out the online behemoth in a “near statistical tie” in its new eCommerce Retailer Preference Index.

“H-E-B’s impressive performance proves that it’s possible to compete and win against Amazon when it comes to grocery e-commerce,” said Grant Steadman, dunnhumby’s president of North America. “Their success offers mid-size and regional retailers a roadmap on how to succeed online.”

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Walmart came in fourth and its Sam’s Club chain was fifth, followed by Kroger, BJ’s Wholesale Club and Sprouts Farmers Market.

H-E-B took the top spot because it had the highest level of emotional connection to customers and online share of wallet, or how much of their grocery spending goes to a specific company, dunnhumby said.

Early in the coronavirus pandemic, more H-E-B customers shifted to purchasing their groceries online. They increased their spending by 27 percent, giving H-E-B the highest share of wallet online in the study.

The firm based its inaugural index on a statistical model informed by an online survey of about 3,000 households that shopped online at least once in the 30 days before the survey. Fifty-four retailers were scored on a range of preference drivers, emotional connection and e-commerce performance.

Dunnhumby also evaluated web traffic, share of wallet online and online penetration of a grocer’s total customer base.

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Retailers who rely more on their own apps and websites “have a clear strength” compared with those that use intermediaries such as Instacart and Shipt because they have more control, dunnhumby said.

Customers also value ease and reliability when deciding where to spend their money online, the company added.

H-E-B has steadily invested in its digital operations. The company started offering curbside pickup in 2015 and has since expanded the option to most of its Texas stores.

H-E-B acquired Favor Delivery in 2018 and doubled its coverage area statewide in 2020, during the pandemic. In 2019, the company launched a new mobile app and opened a technology hub in Austin, which includes Favor’s headquarters.

It has also devoted more square footage at its stores and more employees to preparing and storing online orders.

Madison Iszler covers real estate, retail, economic development, and other business topics for the San Antonio Express-News.

Reach Madison at 210-250-3242, madison.iszler@express-news.net and @madisoniszler.