What are open market operations? The Fed purchases T-bills, right? Maybe that was true at one point, but the Fed's security portfolio has changed.
The Fed currently holds $1.8 trillion in securities, approximately 82% of total assets. Security holdings again dominate the Fed's asset portfolio, but T-bills make up less than 1%. The chart below shows different types of securities as a percent of total securities.
What about the Treasury notes and bonds? While some of them have relatively short terms to maturity, about half are maturing after 2014. The chart below shows T-notes and bonds by their term to maturity as a percent of total T-notes and bonds.