Visa Inc. and MasterCard Inc., the two biggest U.S. payment networks, posted their biggest gains of the year on speculation that U.S. curbs on debit-card fees will be delayed or modified.

Visa advanced $3.04, or 4.2 percent, to $75.24 at 10:20 a.m. in New York Stock Exchange composite trading, the most since June for the San Francisco-based firm. MasterCard jumped $8.86, or 3.5 percent, to $260.57 after gaining as much as 4.2 percent. That’s the best showing since December for the Purchase, New York-based company.

Federal Reserve Chairman Ben S. Bernanke said yesterday that the central bank wouldn’t meet an April 21 deadline to come up with a final rule on debit-card transaction fees. The cap, mandated by the Dodd-Frank law that overhauled the financial industry last year, must be in place by July 21.

U.S. Senator Jon Tester, a Montana Democrat, is pushing for a chamber vote as soon as this week on a bill that could delay the cap by two years.