UPDATE 1-Fed to report Bear Stearns portfolio value

(Adds details of portfolio, benchmark index)

NEW YORK, April 3 (Reuters) - The Federal Reserve Bank of New York said on Thursday it would report on a quarterly basis the value of the assets held as collateral for a $29 billion credit line to JPMorgan Chase & Co (JPM.N: Quote, Profile, Research) as part of its deal to buy Bear Stearns Cos BSC.N.

Bear Stearns said the assets were worth $30 billion, based on market values on March 14.

"We will report the valuation and recoveries from liquidation of the portfolio on a quarterly basis, subject to annual review by our outside auditors Deloitte Touche Tohmatsu," the Fed said in an annex to congressional testimony by New York Fed President Timothy Geithner.

Last month, in a highly unusual move, the Fed provided the financing for JPMorgan to acquire Bear Stearns in order to prevent Bear from going bankrupt and potentially dragging down the entire financial system.

The Fed selected BlackRock Inc to manage the portfolio, which consists of investment-grade securities and residential or commercial mortgage loans classified as "performing."

In the annex, the Fed said the portfolio contains collateralized mortgage obligations, most of which are obligations of government-sponsored entities such as Fannie Mae and Freddie Mac. It also consists of asset-backed securities, adjustable-rate mortgages, commercial mortgage-backed securities, non-GSE CMOs, collateralized bond obligations and various other loan obligations.

Though it is not clear how the securities have performed since March 14, when Bear Stearns valued the portfolio at $30 billion, a benchmark indices that track mortgages have risen.

Total return on Merrill Lynch's U.S. mortgage master index, which tracks the performance of U.S. dollar-denominated 30-year, 15-year and balloon pass-through mortgage securities, fell to the lowest level so far this year on March 6. But since March 14, it has edged up 0.4 percent.

Based on generally accepted accounting principles, the Fed would be required to report the portfolio's value on an annual basis. (Reporting by Kevin Plumberg)