Citigroup Inc. says it’s been told by the Securities and Exchange Commission that the agency has completed its investigation of the bank’s conduct regarding mortgage bonds and won’t bring further enforcement action.

Citigroup said in a regulatory filing Friday that it received the information from the SEC this week.

The SEC has filed a series of cases against Citigroup and other big Wall Street banks in recent years over their sales of securities backed by risky mortgages ahead of the 2008 financial crisis. The banks have paid hundreds of millions of dollars to settle the SEC charges. The five-year statute of limitations for filing such civil cases has imposed a deadline on the agency for bringing enforcement actions.

When the housing market bubble burst in 2007, millions of home borrowers defaulted on their loans and bundles of mortgages sold by big banks left investors with billions in losses.

SEC spokesman John Nester declined to comment.

Citigroup last month agreed to pay $7 billion in a civil settlement over sales of mortgage securities with the Justice Department, state attorneys general and the Federal Deposit Insurance Corp.

In its filing, Citigroup also noted a federal appeals court ruling in June that a judge overstepped his authority when he blocked a $285 million settlement between the bank and the SEC over mortgage securities.

The appeals court in Manhattan reversed a decision by U.S. District Judge Jed Rakoff to set a trial date for the case brought by the SEC in October 2011.

That sent the case back to Rakoff. The appeals court said Rakoff should not infringe on the SEC’s discretionary authority to choose its terms of settlement and should not require the agency to establish the truth of the allegations it made against Citigroup.