The Federal Reserve, which started buying mortgage-backed securities guaranteed by Fannie Mae (FNM), Freddie Mac (FRE) and Ginnie Mae this week, is expected to release its purchase tab around 3 p.m. EST (2000 GMT) Thursday.

The release had initially been expected at 4:30 p.m. EST (2130 GMT) as part of the Fed's balance sheet, which is published every Thursday. But because the purchases haven't settled yet, the data will be published separately on the New York Fed's Web site.

Since Monday, the New York Fed has been buying these mortgage securities in a bid to boost the sagging investor interest in these bonds and stabilize the housing market.

The central bank has said it would buy up to $500 billion of these securities in the first half of the year, and more if needed.

Market participants expect the Fed's purchases to be in the range of $3 billion to $4 billion daily, if it were to keep its aggressive purchase plan.

The extent of Fed purchases is expected to prompt other investors, who had shied away from this market, to return.

The presence of the Fed in the mortgage-backed securities market has pushed risk premiums on these bonds to tighter levels. As a result, mortgage rates that homeowners pay are expected to fall.

-By Prabha Natarajan, Dow Jones Newswires; 201-938-5071; prabha.natarajan@dowjones.com

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