Netflix Inc., the mail-order and online movie-rental service, fell as much as 4.8 percent in Nasdaq trading after Warner Bros. said it will offer films for purchase or rental through Facebook.

Selected movies distributed by Warner Bros. will be available on each film’s official Facebook page, starting today with "The Dark Knight," the company said in a statement. Users can click a “rent” icon and pay with Facebook Credits, the Time Warner Inc. unit said.

Netflix, based in Los Gatos, California, is facing increasing competition from technology companies including Amazon.com Inc. that are expanding into the online movie-rental business.

Shares of Netflix fell $6.62, or 3.2 percent, to $200.78 at 9:57 a.m. New York time in Nasdaq Stock Market trading, and earlier slid as low as $197.50. Before today, the stock had more than tripled in the past year.

Renting a movie through Facebook costs 30 Facebook Credits, or $3. Viewers have 48 hours to watch the films.

“Facebook has become a daily destination for hundreds of millions of people,” said Thomas Gewecke, president of Warner Bros. Digital Distribution, in the statement. “Making our films available through Facebook is a natural extension of our digital distribution efforts.”