American Top 40

American Top 40 (abbreviated to AT40) is an internationally syndicated, independent song countdown radio program created by Casey Kasem, Don Bustany, Tom Rounds, and Ron Jacobs. The program is currently hosted by Ryan Seacrest and presented as an adjunct to his weekday radio program, On Air with Ryan Seacrest. Originally a production of Watermark Inc. (later a division of ABC Radio known as ABC Watermark, now Cumulus Media Networks which merged with Westwood One), American Top 40 is now distributed by Premiere Networks (a division of iHeartMedia).