The insurer's share price has fallen 30 percent since Feb. 14 when it was announced that AIG was subpoenaed by New York Attorney General Eliot Spitzer's office and the Securities and Exchange Commission. The company has lost some $51 billion of market value since then.

There are also reports today that regulators have begun to investigate whether AIG manipulated its underwriting loss ratio by putting a cap on the figure. The Wall Street Journal, citing unidentified sources, also said a lawyer for former CEO and Chairman Maurice Greenberg took out boxes of documents from AIG's Bermuda office last week, obstructing ongoing regulatory investigations.

One investment analyst who helps clients buy stocks including AIG shares said continuing uncertainties surrounding AIG are behind the stock's price fall.

"Rating agencies have downgraded AIG, which is a cause of some concern. AIG hasn't filed its 10-K, which is also causing some concern. And there is the concern about AIG's finite risk arrangement," Thomas Russo from investment advisory firm Gardner Russo & Gardner told National Underwriter. Mr. Russo helps invest some $1 billion for the Lancaster, Pa.-based firm, including AIG shares.

"All these things have come together to create an atmosphere of uncertainty and some investors are selling because they are unwilling to bear such uncertainties."