Shares of U.K. gambling companies including 888 Holdings 888, -3.54%, William Hill WMH, -3.06% and Flutter Entertainment FLTR, -1.78% lost ground Tuesday as the U.K. Gambling Commission announced it would ban them from accepting payments on credit cards. The commission cited data showing 800,000 U.K. customers use credit cards to gamble and 22% of online gamblers who use credit cards to gamble are classed as problem gamblers. The ban is due to go into effect on April 14.