WASHINGTON (Reuters) -Charter Communications has agreed to pay $25 million to settle U.S. Securities and Exchange Commission (SEC) charges related to unauthorized stock buybacks, the regulator said on Tuesday.

From 2017 to 2021, Charter used a provision that changed the total dollar amounts available to buy back stock and the timings of the buybacks after the plans took effect, the SEC said in a statement. Those provisions, which the SEC found the company used in nine separate pre-approved trading programs over those four years, ran afoul of the agency's rules for such plans.

Charter said in a statement that it fully cooperated with the SEC's inquiry and that its share repurchase plans were well-documented and disclosed in financial statements. "We remain committed to a share buyback program and our previously stated leverage targets," the company said.

U.S. regulators have ratcheted up scrutiny of rearranged stock trading programs, known as 10b5-1 plans, in the face of criticism from lawmakers and others. The SEC last year overhauled the rules for such plans to deter insiders from trading on material information that investors do not have.

(Reporting by Chris Prentice in New York and Jasper Ward in Washington; Editing by Bill Berkrot)