Although equities and Treasurys gained on the Federal Reserve officials statements this week, the agency mortgage-backed security market may have gotten the biggest sugar high.

The central bank's current bond-buying program means agency MBS investors have as much stake in the Fed's policies as anyone else and perhaps more.

The net supply of new issuance MBS is just about zero, when accounting for new supply alongside maturing and refinanced debt, said Tom Graff, fixed-income portfolio manager at Brown Advisory, in an interview. When the Fed makes its purchases, it pulls supply directly out of the market, which means the central bank’s effect is magnified.