NEW YORK – Big banks facing big drops in revenue are looking to Main Street to make up the difference.

Checking accounts, bank statements, even popping into your local bank branch could carry a hefty cost as the nation’s mega-banks scramble to offset expected damage from the sweeping financial overhaul. The uncertain future has overshadowed otherwise strong second-quarter earnings at JPMorgan Chase & Co., Citigroup Inc. and Bank of America Corp.

All three companies beat expectations this week with profitable results. Yet their stocks tumbled, helping send the wider market sharply lower Friday.

The reason: Investors are worried about banks’ future earning power after Thursday’s passage of the most dramatic rewriting of banking rules since the Great Depression. Adding to the pessimism are falling trading profits, which all three banks mentioned in their earnings reports, and weak U.S. loan demand.

The worries are well-founded. Bank of America said Friday it could lose up to $2.3 billion in annual revenue alone just from new restrictions on debt card “swipe” fees, or the money banks charge merchants who accept debit cards. All told, the bill’s passage will reduce the value of Bank of America’s lucrative credit card business by a staggering $7 billion to $10 billion.

“This is going to cause a significant reduction in revenue in the future,” Bank of America CEO Brian Moynihan said.

The second-quarter results, driven by a sharp drop in losses from failed loans, would have given Bank of America’s stock a nice bounce in the past. Instead, investors anxious about the future swiftly dumped the shares, which fell 9 percent.

“The easy time of generating revenue will be restricted with regulations,” said Alois Pirker, research director at Aite Group.

Yet banks are already moving to recoup any losses. One approach: making traditionally free services premium offerings. A Bank of America pilot program in Georgia, for instance, charges customers $8.95 a month to get paper statements or use bank tellers. The bank could start the program nationally as soon as next month.

Bank of America is also considering raising minimum balances on some accounts and charging customers who fall below it.

Other banks are considering doing away with the once ubiquitous free checking accounts long used to lure new customers.