Just a day after agreeing to pay about $300 million for about 20% of New York-based hedge fund Avenue Capital Partners, Morgan Stanley consummated its long-running courtship of FrontPoint Partners.

The Wall Street giant confirmed today that is has agreed to acquire FrontPoint Partners for an undisclosed sum, though some insiders say Morgan Stanley is shelling out about $400 million for the $5.7 billion Greenwich, Conn.-based firm. The two sides have been talking about an acquisition for about a year.

FrontPoint is headed by former Morgan Stanley CFO Philip Duff, and features several other Morgan alums among its staff. In addition, the man charged by Morgan CEO John Mack with building the Wall Street giant’s alternatives business, Stuart Bohart, formerly worked at FrontPoint.

FrontPoint has $5.5 billion in assets under management as of October 1, 2006. The transaction is expected to close in December 2006.