William Galvin, the Massachusetts Secretary of Commonwealth, issued a subpoena to Morgan Stanley over an analyst's discussions with investors on Facebook.

"The Securities Division has put out a subpoena to Morgan Stanley in connection with the analyst's discussion with certain institutional investors about the revenue prospects for Facebook," a spokesperson for Galvin's office said on Tuesday.

"Morgan Stanley followed the same procedures for the Facebook offering that it follows for all IPOs.  These procedures are in compliance with all applicable regulations," a Morgan Stanley spokesman said in an emailed statement.

The analyst's revisions came after Facebook revised its prospectus on May 9, which the firm forwarded to all of its retail and institutional clients, according to the statement.

Troubled launch

The much-anticipated social media site's initial public offering has been steeped in controversy since it started trading on Friday. Much of the controversy stemmed from a Nasdaq glitch that caused the stock to delay trading by 30 minutes.

As of Monday afternoon, some customers of Fidelity Investments, Morgan Stanley and Charles Schwab were still waiting to see if their trades for Facebook shares were completed on Friday.

Reuters new agency then reported late on Monday that the consumer internet analyst at lead underwriter Morgan Stanley cut his revenue forecasts for Facebook in the days before the offering, information that may not have reached many investors before the stock was listed.

On Tuesday, the Securities and Exchange Commission and the Financial Industry Regulatory Authority called for a review of the Facebook IPO call. When markets closed, shares were down more than 18 per cent, to end at $31.