High Quality Content by WIKIPEDIA articles! American Top 40 (commonly abbreviated to AT40) is an internationally syndicated, independent radio program created by Casey Kasem, Don Bustany, Tom Rounds and Ron Jacobs. Originally a production of Watermark Inc. (later a division of ABC Radio, now Citadel Media), it is now distributed by Premiere Radio Networks in the United States, Canada, Australia, the Philippines, Singapore, China, India, the United Kingdom, Malaysia and several other territories worldwide.