Updated from 11:07 a.m. to include CEO comments. 

Bricks and mortar retail king Walmart (WMT - Get Report) has pulled out the big guns this year in its efforts to shoot down digital foe Amazon (AMZN - Get Report) .

The latest bazooka shot was fired on Monday as the world's largest retailer said it will acquire e-commerce player Jet.com for $3 billion in cash. It will also give Jet.com $300 million worth of Walmart shares, which will be paid out over time.

Jet.com founder Marc Lore -- a long-time e-commerce entrepreneur -- will assume the leadership of Walmart's U.S. e-commerce operations, the company confirmed on a media call Monday afternoon. Neil Ashe, who currently oversees Walmart's e-commerce operations, will depart. Jet will continue to operate independently. 

In Jet, said the source, Walmart recognizes an experienced management team in digital retail. In particular Lore is an expert in the sector, a source close to the matter said, and he could provide very valuable knowledge on e-commerce.

"Marc points to the future," Walmart CEO Doug McMillon told reporters. 

Walmart expects the deal to close later this year. Shares were recently down less than 1% to $73.

According to the source, Walmart is particularly keen on Jet's "smart cart" technology. The technology recommends savings opportunities to customers such as increasing item quantities, buying items that ship from the same location, waiving returns and using a low-fee payment method. Jet will also help Walmart expand the number of items it sells online, and reach a higher income customer.

The ability of Jet's technology to help Walmart customers save money over time was not lost on McMillon.

"The customer has more choice over the price they pay, they can build a basket of items," McMillon told TheStreet when asked what he really likes about Jet's business model. He added, "It's [building baskets and subsequently saving money on an overall shopping trip] frankly true to the spirit of Walmart's pricing philosophy."

McMillon did acknowledge that integrating the two online platforms -- and getting key Jet technology onto Walmart's website -- will not happen overnight. He also pointed out that Walmart's backing with such things as fulfillment will help to lower costs for Jet, and "achieve profitability sooner."

"A Walmart and Jet.com tie-up could firmly make the e-commerce battle a two-horse race. While Amazon's current lead may make it seem like the race is already won, this combination could make Walmart more competitive as an omni-channel player with an innovative website in Jet.com," wrote Morgan Stanley analyst Simeon Gutman in a new note on Monday. 

The Jet deal comes in the wake of several actions Walmart has taken this year to try and close the competitive gap with Amazon. 

Walmart goes on the offense against Amazon.

Walmart made its new ShippingPass service available to all customers in the U.S., complete with a 30-day free trial, in late June after a test that launched in May. The two-day shipping subscription service mirrors Amazon's successful Prime service. Members to ShippingPass get free, two-day shipping for $49 a year compared to $99 for the similar service at Amazon Prime. 

Meanwhile, Walmart continues to expand its relatively new grocery pickup service to more locations throughout the U.S. Customers place their grocery orders online, choose a time to pick them up and then pull into a designated parking spot when arriving at the store. From there, a Walmart worker brings the groceries to the person's car. WalMart's online grocery pickup service offers about 30,000 items, including fresh meat, dairy and produce.

Walmart's grocery service takes aim at AmazonFresh, the Internet giant's online grocery business that originally rolled out in Seattle in 2007 and delivers groceries straight to a person's house within hours. To access the service, a person needs a Prime Fresh subscription that costs $299 a year. Order minimums are $50.

The service has since expanded to New York, New Jersey, Pennsylvania, Connecticut, California and Maryland.
Despite its barrage of efforts this year, Walmart will likely have a ways to go before it seriously closes the sales gap with Amazon. Walmart's e-commerce sales were about $14 billion last year -- a mere 3% of its $482 billion in annual sales.
The acquisition of Jet by Walmart for a lofty $3 billion may not even slow down Amazon's e-commerce stronghold. Said Gutman, "We question Jet.com's ability -- even if it is were to be owned by Walmart -- to materially impact Amazon's ability to continue to grow its customer base, Prime user base, or share of wallet per customer. If anything, we see Walmart's acquisition of Jet.com as defensive/reactionary to Amazon's accelerating share gains."
Amazon's revenue, meanwhile, was $107 billion last year, including its web-services business. While Walmart's e-commerce sales have continued to slow this year, Amazon has continued to thrive. 
Amazon's worldwide net sales growth has accelerated for two straight quarters, according to company filings. Worldwide net sales growth in the second quarter for Amazon clocked in at 30% year over year, quicker than the 29% in the first quarter.