Liquidnet trading system targets $500 million from IPO

Liquidnet Holdings has filed with the SEC its intention to go public by selling as much as $500 million in shares with its IPO. Liquidnet offers a "dark pool" of trading that allows institutional investors to trade large blocks of equities anonymously. Average daily U.S. trading volume increased 32% in 2007 and 41% in the first quarter of this year. Liquidnet's risks include that it might draw regulatory oversight and that trading volumes could decline and cut into transaction fees.