(FORTUNE Magazine) – Attention, credit card holders who have shopped around for the lowest interest rates: Cash-strapped banks have sold about $9.7 billion of their credit card accounts this year, and some new owners have already increased what you must pay on your balance. For example, Chicago's Household International, which bought Empire of America's credit card portfolio a year ago, increased Empire's interest rate from 13.9% to 18.9%. Next could be People's Bank of Bridgeport, Connecticut. People's, which also charges 13.9%, is trying to sell one-third of its $600 million credit card portfolio. The law requires banks to announce interest increases. But only Delaware insists that banks allow cardholders to pay off old balances at the former rate. Congressman Charles Schumer (D-New York) has proposed a bill that would extend the Delaware law nationwide. - R.T.