The Federal Reserve bought $15.0 billion net of agency mortgage-backed securities in the latest week, the New York Fed said on its website on Thursday.

That is down from the previous week's net purchases of $16.0 billion.

The purchases brought the U.S. central bank's purchase of mortgage bonds guaranteed by Fannie Mae, Freddie Mac and Ginnie Mae to roughly $1.102 trillion since January.

The Fed said it bought $17.430 billion gross of agency MBS from December 17 through December 23. At the same time, it sold $2.430 billion in mortgage securities.

The Fed aims to buy $1.25 trillion of agency MBS in a bid to bring down mortgage rates and to stimulate the battered housing sector and the overall economy.

(For more details on the purchases, please click on: