A review of the Federal Reserve's response to recent leaks about its bond-buying plans raises new questions about the central bank's efforts to police interactions with investors who can profit handsomely from inside information.

In January 2011, the Fed adopted new rules for dealing with breaches, after a private research firm published an account of the central bank's deliberations. Under the policy, an internal watchdog – the agency's inspector general – was responsible for conducting investigations.

But the next year, when a different research firm revealed details to its clients about a new round of bond-buying, Fed officials did not tell the inspector general or law enforcement about the breach. They spent nearly six months conducting their own investigation; they didn't find the source of the leak.