The Fed has taken on more than $2 trillion in mortgage-backed assets in the past couple of years. The final Fed purchase was concluded at the end of March.
"The Fed has gone beyond was was viewed as its historical authority in the last two and a half years without any transparency or accountability," Grassley said. "Our amendment changes that by making the Fed's emergency loan authority subject the light of day."
In 2009, the two Senators worked with a bipartisan group of 11 lawmakers to force the Fed to disclose the information.