WASHINGTON (MarketWatch) -- To implement the Federal Reserve's new policy of quantitative easing, the New York Fed plans to buy $850 billion to $900 billion in Treasury notes over the next five months, including $600 billion in new purchases and about $250 billion to $300 billion to reinvest the proceeds of maturing mortgage-backed securities, the New York Fed announced Wednesday. The average duration of Treasurys purchased by the Fed will be five to six years. Around the eight day of each month, the Fed will announce the details of that month's planned purchases.