NEW YORK (Reuters) - A fast-growing market for private placements of stock has emerged to rival the initial public offering as a way for U.S. companies to raise capital by selling shares.

Last year, the value of private placements of unregistered stock, or 144A transactions, reached $162 billion, outpacing the $154 billion raised in public offerings, according to Nasdaq Stock Market (Nasdaq:NDAQ - news).

“For the first time that we have been able to tell, the 144A marketplace has become comparable to or even slightly larger than the U.S. traditional equity marketplace,” said Nasdaq Executive Vice President John Jacobs.

This year too, the volume of private placements is running just ahead of IPOs, according to research firm Dealogic.

Private placements have become increasingly popular with companies that want to raise capital without many of the regulatory and disclosure requirements that come with a public listing.

For such companies, private placements — which are restricted to qualified institutional buyers with at least $100 million of assets — are often quicker, easier and less expensive than an IPO.

What’s more, trading information platforms developed by FBR Capital Markets (Nasdaq:FBCM - GS - news), Nasdaq and others are set to make privately placed stock more liquid. That amounts to a wider marketplace in which to trade these unregistered securities.

“This is a way to still essentially have your securities trade primarily in the United States on the desk of a domestic broker-dealer but not have to comply, at least initially, with all the Sarbanes-Oxley requirements,” said FBR Capital Markets Chief Operating Officer Rick Hendrix.

“It is a new market in the sense that more and more companies are availing themselves of this exemption from the registration requirements in the United States,” added Hendrix, whose firm is also a prominent player in private placements.