Walmart (NYSE:WMT) has added another e-commerce trophy to its growing list of accolades: The big-box retailer has surpassed online pioneer eBay (NASDAQ:EBAY) for a share of e-commerce sales in the U.S. for the first time in May 2020, according to eMarketer.

eBay has long trailed digital sales leader (NASDAQ:AMZN), which accounts for 38% of online shopping in the country. Walmart has now moved into the No. 2 spot with 5.8% of digital retail, while eBay slipped into third with 4.5%.

A smiling couple making an ecommerce purchase using a laptop to enter credit card information.

Image source: Getty Images.

During Walmart's first quarter, which ended May 1, the company reported e-commerce sales that jumped 74% year over year, with strong contributions from its grocery pickup and delivery services,, and its marketplace. During eBay's first quarter, which ended March 31, its marketplace revenue -- which excludes its classifieds business -- fell 1% year over year. This illustrates that Walmart was gaining share as eBay was losing it, even in a period that was a strong one for digital sales. 

E-commerce sales in the U.S. increased nearly 15% year over year during the first quarter of 2020 and accounted for 12% of total retail, according to the U.S. Department of Commerce. 

eMarketer estimates that e-commerce sales will increase 18% year over year in 2020, eclipsing its earlier forecast of 13% growth. At the same time, overall retail sales are expected to decline 10.5%.

There has been a widely reported shift in consumer buying behavior as the result of the COVID-19 coronavirus pandemic. With widespread stay-at-home orders and employees shifting to remote work, many customers choose the ease and convenience of e-commerce, foregoing trips to brick-and-mortar retail stores for fear of contracting the virus. Unfortunately, eBay was unable to capitalize on the shift.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.