“Public pension disclosure by municipal issuers continues to be a top priority,” said Elaine C. Greenberg, chief of the S.E.C.’s Municipal Securities and Public Pensions Unit, which was formed in 2010.

Its first action against a state accused New Jersey of fraud that year in connection with pension disclosures that said a special reserve had been set up to pay for pension increases. The reserve was an accounting illusion, The New York Times had previously reported.

In that case, as with Illinois, the S.E.C. has cited the harm done to the investors who bought the governments’ bonds — not the retirees whose pensions were at risk, or the taxpayers who found themselves expected to make outlays they never agreed to. The S.E.C.’s mission is to uphold the integrity of the capital markets, not to protect retirees or promote balanced budgets.

“Municipal investors are no less entitled to truthful risk disclosures than other investors,” George S. Canellos, acting director of the S.E.C.’s Division of Enforcement, said in a statement. “Time after time, Illinois failed to inform its bond investors about the risk to its financial condition posed by the structural underfunding of its pension system.”

The S.E.C. noted that Illinois had passed a law in 1994 allowing itself to put less than the required amount into its pension system each year. It is not the only state to have done so. For the next 15 years, Illinois issued annual reports showing that it was on track with its lawful schedule, even as it fell further behind the real-world amount needed to pay all current and retired public employees.

By 2003, the state was so far behind that it issued $10 billion of bonds and put the proceeds into its pension funds to make them look flush. The main underwriter of those bonds, Bear Stearns, was later found to have made an improper payment to win the business, figuring in the corruption trial of a former governor, Rod R. Blagojevich.

In 2005, the state passed another law, giving itself a holiday from making even the inadequate annual pension contributions called for by its 1994 schedule. It said it would offset the missing money with bigger contributions from 2008 to 2010, but then did not do so. By 2010, the reported shortfall of the pension system was $57 billion, and senior officials were warning that the system was at risk of breaking down completely.