SecondMarket, which offers an online platform to match buyers and sellers in privately held companies, is seeking U.S. approval to handle those transactions, according to the Wall Street Journal on Sunday.

The New York-based firm, which is now the largest vendor for trading shares in closely held companies such as Facebook, Groupon and Twitter, has held preliminary talks with the Securities and Exchange Commission about a potential no-action letter, said the newspaper.

This would guide SecondMarket, which is already a registered broker-dealer with the SEC, on how to operate.

The discussions come amid deepening scrutiny of trading on secondary markets like SecondMarket and SharesPost. Both companies have been growing at a rapid pace over the last two years.

A SecondMarket spokesman declined to comment.

(Reporting by Nadia Damouni in New York; Editing by Muralikumar Anantharaman)