As if promising two-day delivery wasn't enough, Amazon just raised the bar for retailers across the U.S. — chiefly Walmart and Target — to offer even faster and cheaper shipping for online purchases. Or to lean into their bricks-and-mortar stores, something Amazon can't do, even more.

The e-commerce company announced Thursday that it will be making one-day shipping the standard for all Amazon Prime members, expecting to spend $800 million during the second quarter of this year to improve its warehouses and delivery infrastructures to make this possible.

Target shares closed Friday down almost 6%. Walmart shares tumbled 2%. Amazon's stock closed the day up 2.5%.

With more than 100 million paying Prime members across the country, it's estimated Amazon reaches more than 50% of U.S. households today, and growing. And so the impact of its move toward an even speedier shipping option is going to be substantial. This means more and more consumers are going to get used to having whatever they order on the internet show up at their doorsteps in 24 hours or less. Walmart and Target are going to need to make sure they meet these changing expectations.

Already, nearly 40% of consumers want online orders to arrive in two days, free of charge, according to a survey by the National Retail Federation of about 3,000 U.S. adults from Oct. 23 through Nov. 30 of last year. Twenty-nine percent of people said they didn't complete a purchase online after finding out two-day shipping wasn't free.

"Just as Amazon did with Prime 2-day delivery 14 years ago, we see a broad-based 1-day shipping offering increasing consumer e-commerce expectations (essentially more people will get used to 1 day vs. 2 day shipping … and grow to expect 1-day shipping)," Morgan Stanley analyst Brian Nowak said in a research note.

"This, in our view, is likely to cause other brands, manufacturers, retailers, and logistics companies to have to invest more aggressively to compete with Amazon and its differentiated delivery," he added. "The cost to compete within e-commerce continues to rise."