The Federal Reserve is giving U.S. banks two more years to ensure their holdings of certain complex and risky securities don't put them afoul of the new Volcker Rule.

The Fed's move announced Monday didn't give banks an outright exemption for the securities from the Volcker Rule's ban on high-risk investments. Wall Street banks had sought an exemption and the leading Wall Street lobbying group expressed disappointment with the Fed's move.

The Volcker Rule, adopted in December, is intended to limit banks' riskiest trading bets that could implode at taxpayers' expense. That kind of risk-taking on Wall Street helped trigger the 2008 financial crisis. Congress mandated the Volcker Rule in its financial overhaul law.

The Fed gave banks until July 2017 to "conform" their holdings of the collateralized loan obligations, which are mainly backed by commercial loans.

The Fed previously had given banks a one-year extension, to July 2015.

Banks had contended that without an exemption, they would be forced under the Volcker Rule to shed their CLO securities at a disadvantage.

"Any forced selling of these securities will ... damage a key source of funding for Main Street businesses" by distorting market prices for the securities, Kenneth Bentsen, president of the Securities Industry and Financial Markets Association, said in a statement.

Dennis Kelleher, the president of Better Markets, a group that advocates strict financial regulation, said many of the securities in question will mature in a few years so banks won't have to sell them to comply with the rule.

The banks' lobbying for an outright exemption "was just a Wall Street politically manufactured issue," Kelleher said. He called the Fed's action "a pretty narrow tweak" applied to a specific type of security.

The rule is named for Paul Volcker, a former Federal Reserve chairman who was an adviser to President Barack Obama during the financial crisis. Volcker urged a ban on high-risk trading by big banks to diminish the likelihood that taxpayers might have to rescue them, as they did after the financial crisis.