The Federal reserve announced Operation Twist, an action from 1961 where the Fed swaps out treasuries of short maturity lengths, for longer ones, all in an attempt to flatten, or twist the yield curve. From the Economist:

Operation Twist has long been considered a failure. Early studies found little impact on yields, vindicating those who argued that the price of a security depends only on expectations—of inflation, for example, or monetary policy—not its relative supply. Eric Swanson, an economist at the Federal Reserve Bank of San Francisco, disagrees. Previous studies, he reckons, didn’t properly isolate the influence of Operation Twist from countervailing factors. By studying the behaviour of bonds right around announcements related to Operation Twist, he concludes the programme lowered yields by 15 basis points in total.

From the FOMC statement: