A man walks up the steps of the U.S. Supreme Court on January 31, 2017 in Washington, DC.

The Supreme Court said Friday that it will hear a case between retirees and US Bank concerning whether members of a pension plan can sue the fund manager even if the plan is overfunded.

The plaintiffs, retirees of US Bank, allege that those running a defined benefit failed to properly diversify investments and introduced unnecessary risk, leading to $748 million loss for the plan from September 2007 to December 2010. The plaintiffs say FAF Advisors, a US Bank subsidiary at the time, invested all of the plan in the stock market despite the plan being overfunded, taking on risk and increasing the chances of insolvency.

As the case worked its way through the courts, the pension plan became overfunded once again in 2014, leading a district court to dismiss the case. The Eighth Circuit Court of Appeals later affirmed the decision.

The federal government recommended a grant in this case on June 5. The case involves the Employee Retirement Income Security Act of 1974, where funding status is based on several different factors, including actuarial tables and inflation.

"Given normal fluctuations in those bases and assumptions, it is easy to imagine a plan toggling somewhat frequently between overfunded and underfunded," the government's amicus brief said. "It would be bizarre to tether a plaintiff's standing — and thus a federal court's power to hear a case — to such a volatile and arbitrary metric."

The case will be heard in the court's next term, which begins in October.