NEW YORK — On the eve of the bull market’s second anniversary, billionaire investor Carl Icahn had an unsettling message for his investors: Take your money back.

Icahn told investors in his hedge funds that he didn’t want to be responsible to them for “another possible market crisis,” especially given the rapid increases over the past two years. Stocks have nearly doubled since hitting 12-year lows on March 9, 2009.

Icahn, who has built a fortune from taking stakes in well-known companies and then pressing for changes, also said he was concerned about the economic outlook and political tensions in the Middle East. Icahn’s targets over the years have included Yahoo Inc., RJR Nabisco and Revlon.

Jack Ablin, chief investment officer at Harris Private Bank, said Icahn is likely trying to avoid regulatory scrutiny. Under new laws, hedge funds have to register with the Securities and Exchange Commission and allow the agency to inspect them.