Walmart has a secret weapon that could one-up Amazon - but it hasn't released it yet

Walmart has been aggressively investing in ecommerce to catch up to rival Amazon.

The retailer is cutting back on store growth over the next several years as it invests in digital, the company said Thursday ahead of its annual investor day in Bentonville, Arkansas.

Walmart will open 130 US stores this year, down slightly from the 135 to 155 stores it had originally projected, and also down from the 230 stores that were opened last year.

Next year, it will open just 55 US stores, half of which will be its smaller-format Neighborhood Market stores.

In the meantime, Walmart has doubled its online fulfillment warehouses in the last year to 10, Reuters reports. Industry experts had expected Walmart to have just eight warehouses by the end of 2018.

Amazon currently offers offers two-day delivery to members of its Prime program, who pay $99 annually for the service.

The company says it's now capable of shipping packages to 70% of America within one day, according to Reuters. But it can't do so profitably, so it hasn't rolled out the service or advertised it to customers just yet.

Walmart has been ramping up investments in ecommerce as it tries to catch up to Amazon, which had $107 billion in online sales last year, compared to Walmart's $13.7 billion in online sales in the period.

As part of its bid to take on Amazon, Walmart recently purchased online retailer Jet.com. The company has said it expects Jet.com to accelerate its ecommerce growth.

"We are encouraged by the progress we're seeing across our business and we're moving with speed to position the company to win the future of retail," Walmart CEO Doug McMillon said in a statement Thursday. "Our customers want us to run great stores, provide a great e-commerce experience and find ways to save them money and time seamlessly - so that's what we're doing."

Disclosure: Jeff Bezos is an investor in Business Insider through hispersonal investment company Bezos Expeditions.