Marketing credit cards: offers you can't refuse.

If there is one secret that is the most guarded in a bank's arsenal of competitive strategies, it is credit card marketing. Here's what banks are doin to retain customers.

Ranked as one of the most profitable products a bank offers, credit cards still are racking up some impressive returns on assets, anywhere from 2 percent to 3. percent. Many bank marketers believe assets like that are not only worth fighting for, they are worth safe-guarding.

"Competition is cutthroat right now," says Michael Auriemma, managing director of Auriemma Consulting Group, a Westbury, N.Y., firm that advises banks on managing their credit card portfolios. "More issuers are fighting for market share."

Part of the reason competition for market share is so intense, is most of the consumers who are creditworthy already have been issued credit cards. One way t gain new accounts is to lure them away from other issuers. Some strategies include offering low introductory rates for transfer balances, developing co-branded cards, and building exceptional card value by offering consumers something in return for use.

"Cannibalization is what many marketing strategies are about," says Auriemma. "You're not finding a new population, you're shifting market share and moving people from one product to another."

One account acquisition strategy many issuers use is to offer a low introductor rate for balances transferred from another card. The low interest rate is usually in effect for anywhere from six to 18 months, and afterward, any portio of the unpaid transfer balance is assessed the card's transaction interest rate Auriemma has seen offers as low as 6.9 percent, but the majority are between 7. percent and 8.9 percent. "To be effective the rate has to be in the single digits and lower than 9 percent," he says. "But you have to be careful the rate doesn't get too low, because then it becomes unbelievable to consumers. If it i below prime, people think it is a hoax."

Since the low rate on transfer balance is a recent phenomenon, credit card issuers are waiting to see if the strategy has paid off. Auriemma says so far, it has been successful in moving significant amounts of money. AT&T's Universal Card first made such an offer available to its customers from April to June 1992. The offer contributed to moving more than $1 billion into its portfolio, said Bruce Reid, spokesperson for AT&T Universal Card. The question is still unanswered as to whether customers remain loyal once the transfer balance is paid off, or jump to another program with a better offer.