The move, long anticipated by investors, makes it harder for travelers to attain elite status and benefits on American by booking flights on the cheap that log thousands of miles. It follows similar changes to the loyalty programs of Delta Air Lines Inc and United Continental Holdings Inc.

American had held off on the switch while integrating the loyalty program and reservations platform of subsidiary US Airways so customers and employees were not overwhelmed by change. The two companies merged in 2013 to form the world's largest airline.

Frequent fliers will earn five award miles for every dollar spent on tickets, with elite members earning higher amounts.

American also said it was lowering the number of miles travelers needed for free flights to destinations in Latin America. Miles needed on some flights to Asia and Europe "will increase due to changes in market pricing and demand," it said in a news release.

"It will be accretive to (American's) bottom line as it's a more efficient program and (it's) harder to game the system," Sterne Agee CRT analyst Adam Hackel said.

Shares fell more than 1 percent, although Hackel attributed this to jitters about demand for travel to France in light of attacks Friday in Paris that killed 129 people.

"This isn’t doomsday," said travel writer Brian Kelly in a post on his website, ThePointsGuy.com. "There will be winners (people who spend more and fly on expensive tickets) and losers (economy-class international flyers)."

(Reporting By Jeffrey Dastin in New York; Editing by Christian Plumb and Jonathan Oatis)

By Jeffrey Dastin