U.S. lawmakers are looking into issues with Facebook's initial public offering, amid allegations that information about the company's ability to make money was withheld from some investors.

The Senate Banking Committee says its staff will meet with Facebook officials, regulators and other stakeholders. A spokeswoman for the House Financial Services Committee says staff members are being briefed on the issue and the topic will likely be raised in hearings.

The Securities and Exchange Commission and the Financial Industry Regulatory Authority — Wall Street's investigative arm — have also called for a review of Facebook's IPO. Massachusetts state regulators have subpoenaed investment house Morgan Stanley, the top underwriter of Facebook stock.

Facebook shares have lost 16 percent of their value since going on sale Friday at $38.

Reuters reports that Morgan Stanley analysts revised their revenue outlook for Facebook downward in the days before it went public, based on a new Facebook stock prospectus. Reuters says Morgan Stanley shared that information with large investors, but held it back from small investors, who expected the $38 price to rise. Morgan Stanley says it did nothing wrong.

Several investors have sued Facebook for not disclosing information.

Along with questions about the price of shares, the NASDAQ stock exchange says it mishandled trading in the stock. NASDAQ said its technology could not cope with the huge volume of stock trades on the first day and might pay damages to investors who lost money because of the problem.