ANZ has ceased issuing American Express credit cards and will close down existing cards from early August, a measure that will cut out a costly reward program for the bank.American Express still has "companion card" arrangements with three other big banks, CBA, NAB and Westpac, but the future of each of those relationships may also be vulnerable.Those arrangements date from around 2004, as banks looked to bypass regulatory activism on credit cards.ANZ confirmed it will no longer offer American Express 'companion cards' with new rewards credit card accounts, effective from 1 March. The bank said existing customers could keep using their existing ANZ American Express card until 5 August, with no change to the number of rewards points they earn on eligible purchases.Andrew Duncanson, data services director at product comparison service Mozo, wrote yesterday that "the benefit of Amex companion cards originally was that they weren't subject to the Reserve Bank of Australia regulations on interchange fees between the merchant's bank and the card issuer. Because companion cards didn't have limits on interchange fees, they could offer more points per dollar than a Visa or MasterCard."Duncanson said that new RBA regulations bring Amex companion cards under the same interchange fee rules as the four party scheme from July 2017.Thus, Duncanson wrote, "from that date, banks won't be able to afford the higher points anymore which means Amex companion cards will become extinct."Megan Whiteside, senior manager for public affairs at American Express, said that "while we have had a very successful partnership with ANZ, we understand the decision in the context, and as a consequence of, the current regulatory environment."ANZ may be looking for more savings on card rewards, while also making its Visa cards a plausible option for those with a bank issued Amex card.The points earn rates of the now standalone Visa rewards cards have been bumped up, Duncanson said, "although not to the same level as the American Express companion cards offered and with a catch. "While the majority of ANZ rewards cards previously offered uncapped points earning, they will now all work on a tiered points scheme. In most cases, this means that rewards value will halve once a certain monthly spend limit is reached."