What is the relationship between Amex and American Express in the context of the input sentence. Choose an answer from: product/material produced; manufacturer; distributed by; industry; position held; original broadcaster; owned by; founded by; distribution format; headquarters location; stock exchange; currency; parent organization; chief executive officer; director/manager; owner of; operator; member of; employer; chairperson; platform; subsidiary; legal form; publisher; developer; brand; business division; location of formation; creator.

However American Express cards are not affected by the rule changes for the moment so it could pay to switch to an Amex card, many of which offer cashback deals.

Answer: operator