Fast food chain McDonald's Corp said on Thursday it would make its popular "Quarter Pounder" hamburgers with fresh beef, prepared when ordered, by mid-2018 in most of its U.S. restaurants.

Investors and analysts said the move, which would compete with rival Wendy's Co's promise of "fresh never frozen beef", could bolster sales but would require restaurant operators to make changes to cooking routines that could slow service.

The change, which does not affect the Big Mac and other beef products, follows a trial run in about 400 restaurants in Texas and Oklahoma that was well received.

"We received overwhelmingly positive feedback from customers and employees and we're proud to have been part of a test that is creating a watershed moment for McDonald's," Dallas/Fort Worth franchisee Joe Jasper said in a statement.

In a short video, McDonald's chief executive Steve Easterbrook said the company also was testing other customer-friendly changes such as home delivery, curbside check-in and mobile order and pay.

Easterbrook was installed as chief executive in 2015 to boost flagging sales. Changes have included the rollout of all-day breakfast in the U.S. market, moving to cage-free eggs, and removing artificial preservatives from several menu items.

Easterbrook has focused on improving nuts-and-bolts operations, but Thursday's announcement is the latest menu tweak after rivals like Wendy's already touted their fresh beef burgers.

McDonald's in January reported slightly lower fourth-quarter earnings, with a drop in comparable sales in the U.S. offset by gains in foreign markets, including China, Japan and some Latin American countries.

Shares of McDonald's rose 0.4 percent to $129.32.