Federal investigators are looking into New Jersey’s underfunded pension system after a report found the state diverted billions of dollars from it for other purposes. The state Treasury Department, in a statement, said it was contacted in late April by the Securities and Exchange Commission for an inquiry into the pension system that has gone largely unfunded from 1993 through last year. The Treasury statement said the SEC is sharing information with the U.S. Attorney’s Office and that the state is fully cooperating. The inquiry follows an April report by The New York Times that found the state recorded investment gains immediately when the markets went up, then delayed recording losses when the markets went down. The newspaper report also found that money used to pay for health care costs was reported as contributions to the pension fund, and that the fund had excess assets that allowed it to divert pension contributions to other uses, such as aid to poor schools. New Jersey’s pension fund is the nation’s ninth largest, with reported assets of $79 billion but an estimated deficit of about $25 billion. Local governments and schools largely fund pensions through property taxes, which are the highest in the nation in New Jersey. The pension funds provide retirement benefits to teachers, judges, prosecutors, state and local police, firefighters and state, county and local government workers. The benefits granted to those workers are guaranteed by state law and cannot be reduced.