Liquidnet Inc., a so-called dark-pool operator that specializes in keeping big investors’ stock-market bets out of the public eye, plans to launch a platform that will enable trading in privately held companies like technology firms Facebook Inc. and Twitter Inc.

Liquidnet on Monday said it will expand into the fast-growing market of trading shares in private and pre-initial-public-offering companies in a bet that its institutional clients will be open to expanding into the private arena. The announcement comes as trading in unlisted companies has expanded rapidly in recent years on platforms such as SecondMarket Inc. and SharesPost Inc.

The value of all private-share transactions was $4.6 billion in 2010, up from $2.4 billion in 2009, according to New York-based research firm Nyppex Holdings. Volume could reach nearly $7 billion this year.

via Dark Pool Looks to Bring Pre-IPO Firms to Institutions – WSJ.com.