Dive Brief:

• With one of the fastest growing e-commerce businesses in retail, Walmart (including Walmart, Sam’s Club and Jet.com) is about to overtake Apple as America’s No. 3 e-retailer, according to the latest forecast from eMarketer. The estimate comes as the retail giant registered 43% growth in e-commerce in its third quarter, with a 32% rise just in the U.S.

• By the end of the year, Walmart will grab 4% of all online retail spending in the U.S., totaling $20.91 billion, up from the research firm’s 3.7% forecast from July, according to the study, which was emailed to Retail Dive. Apple’s share will remain at 3.9%, while Amazon will blow them both away with its 48% share of U.S. e-commerce, and nearly 5% of all U.S. retail sales, according to eMarketer.

• This year, Walmart is on track to grow its online sales 39.4%. By comparison, Wayfair clocks in with an estimated 40.1% growth rate, while Apple will grow just over 18% this year — less than last year — and Amazon’s rate will be just over 29%.

Dive Insight:

Apple is already facing wary investors as sales of smartphones and tablets seem to be flattening somewhat, and that also may be undermining its e-commerce growth, according to eMarketer's report. But the tech specialty retailer has blurred its online and offline channels to a great extent, and is even preparing to sell through Amazon, according to CNET.

There should be little surprise that Walmart could catch up to Apple online, considering the scope of its operations and the range of its merchandise. The retailer first lit a fire under its e-commerce strategy with the acquisition of Jet two years ago, but since then has also bought up a slew of specialty players in apparel and furniture that sell almost exclusively online. In its latest quarter, its digital sales growth came with healthy profits as well.

“Walmart’s e-commerce business has been firing on all cylinders lately,” eMarketer principal analyst Andrew Lipsman said in a statement. “The retail giant continues to make smart acquisitions to extend its ecommerce portfolio and attract younger and more affluent shoppers. But more than anything, Walmart has caught its stride with a fast-growing online grocery business, which is helped in large part by the massive consumer adoption of click-and-collect.”

Grocery may be helping Walmart snag and keep customers, but its growth online is broad, with the retailer gaining "market share in every major online category" in the last year, according to research from GlobalData Retail. "Some of this is down to the various strategic acquisitions the company has made, but a lot is also a function of the investments that have been put into the e-commerce business," GlobalData managing director Neil Saunders said in comments emailed to Retail Dive.

The question for the retail giant, then, is not so much whether it can or can't overtake Apple, but rather, how close it can get to Amazon. So far, despite Walmart's advantages in grocery and the sheer size of its physical footprint, which helps with fulfillment and omnichannel, Amazon is mostly out of reach online.

"The relaunch of the core Walmart.com site is delivering and the improved design, extended selection, and increased range of delivery and pick-up options have been well received," Saunders said, noting that the company's website is pleasing more shoppers, including younger ones. "That said, there is more work to do here in making Walmart.com the first port of call for shoppers who are very used to defaulting to Amazon and who are increasingly locked into the ecosystem of the online behemoth."