Citigroup Inc (C.N) Friday sued AT&T Inc (T.N), saying the phone company infringed its trademarks in the phrase “thankyou” by using the terms “thanks” and “AT&T thanks” in a new customer loyalty program.

The fourth-largest U.S. bank filed its complaint in the U.S. District Court in Manhattan. It seeks a halt to any infringements, triple and punitive damages and other remedies.

AT&T did not immediately respond to requests for comment.