UPDATE 1-REIT DuPont Fabros Technology IPO raises $640.5 mln

(Updates with background, market capitalization, use of proceeds)

NEW YORK, Oct 18 (Reuters) - An initial public offering from real estate investment trust DuPont Fabros Technology Inc raised about $640.5 million on Thursday, pricing at the top of a forecast range.

The Washington, D.C., company, which manages and leases data centers to technology firms, including Microsoft Corp (MSFT.O: Quote, Profile, Research, Stock Buzz), Yahoo Inc (YHOO.O: Quote, Profile, Research, Stock Buzz) and Google Inc (GOOG.O: Quote, Profile, Research, Stock Buzz), priced its offering of 30.5 million shares at $21 per share. Its forecast range was $19 to $21, according to an underwriter.

The offering ranks as the largest U.S. IPO by a REIT year to date, and ranks as the seventh largest REIT IPO ever, according to data tracker Dealogic.

Based on its offering price, the company has an initial market capitalization of about $650 million.

The company's largest shareholders are Chairman Lammot du Pont and Chief Executive Hossein Fateh, according to its registration statement with the U.S. Securities and Exchange Commission.

The company plans to use proceeds to pay down debt.

Underwriters, led by Lehman Brothers LEH.N and UBS Investment Bank (UBSN.VX: Quote, Profile, Research, Stock Buzz), have the option to purchase an additional 4.58 million shares to cover overallotments.

The company has been approved to list its shares on the New York Stock Exchange under the symbol "DFT" DFT.N. (Reporting by Lilla Zuill)