The new FIMA Repo Facility is the Fed's latest move to relieve stresses in financial markets resulting from the coronavirus crisis.
The banks' diminished ability to supply funding at short notice could have "amplified the repo rate reaction" in September, a report says.
Shorting premium Treasury bonds helps companies deduct unused capital losses while providing protection against rising interest rates.
However, financial regulators failed to find a single, root cause for the unusually volatile day on the U.S. Treasury market last year.
