Costco will stop accepting American Express next year

Costco members, you'd better make sure your checkbook is stocked. For 16 years, the wholesale market has accepted only American Express credit cards, along with cash, checks, and Visa and MasterCard debit cards. On Thursday, AmEx said that it had failed to reach a deal with Costco that "would have made economic sense," and that their unusual exclusive arrangement would end March 31, 2016. AmEx's stock price dropped 6.4 percent on the unexpected news. American Express also offers a Costco-branded...