But the services themselves will also aid Wal-Mart’s bottom line. Ms. Thompson said that Wal-Mart’s financial services products provide “healthy margins,” and that she expects the overall business to grow 30 to 40 percent over the next year.

Image Jane J. Thompson, the president of Wal-Mart financial services, called the prepaid cards and money center services foundational products. Credit... Brendan McDermid/Reuters

Much of what Wal-Mart announced yesterday will be directed at consumers who do not use banks. Wal-Mart says, for example, that 20 percent of its customers — about 27 million people — do not have checking accounts. The so-called Wal-Mart Money Card, to be issued with GE Money, a division of General Electric, would allow customers to transfer their paychecks directly onto their cards and make purchases at any retailer that accepts Visa cards. It will also allow them to check their balances online or on mobile phone, pay certain bills or withdraw cash from A.T.M.’s.

The prepaid card will initially cost $8.95, and comes with a $4.95 monthly maintenance fee. Cash can be loaded on the card free by cashing a payroll or government check at Wal-Mart or having the money directly deposited; otherwise, cardholders must pay $4.64 to reload it.

Those without a bank account can “finally take advantage of more mainstream financial services,” Ms. Thompson said. It also could position the retailer to offer new services, like an interest-bearing savings feature that Ms. Thompson said Wal-Mart was considering.

Analysts said there was ample evidence that Wal-Mart would lower the costs of banking in the United States. The chain has already cut the cost of cashing checks by 50 percent, and its financial services saved customers $245 million last year, according to company executives.

Wal-Mart has never hidden its banking ambitions, but it has arguably masked them from time to time. In 2005, Wal-Mart said it would seek permission to open a bank in Utah that would process credit and debit card transactions for its 4,000 American stores. At the time, it vowed that it would never use the bank to enter the consumer financial services business.

Nevertheless, opposition to its plans, which required the approval of federal regulators, swelled. Dozens of banking and corporate watchdog groups testified at hearings outside Washington.