Yes, the company has named a new chief executive, who comes from a solid background at MetLife, and yes, he has said that A.I.G. will pay back the government for its bailout sooner rather than later. The giant insurer has been moving to change the names of key business units and working to disentangle its bewildering structure. It even reported a profit in its latest quarter.

Image The recently selected chief of A.I.G., Robert Benmosche, said he would rely on the ousted chief, Maurice R. Greenberg, for advice. Credit... Nikola Solic/Reuters

But none of that really explains the recent gains. Speculation swirls daily that some deal may be in the works, that short sellers are being squeezed out of their positions, or that the company’s former chief executive, Maurice R. Greenberg, may be poised to make a comeback in the role of consultant. The new chief executive, Robert Benmosche, has been fueling some of the interest, as he talks about seeking advice from Mr. Greenberg and slowing the breakup of A.I.G. so it is not a fire sale.

Mr. Fitzpatrick said he thought the likelier explanation for the increased share price was that speculators looking to profit from a distressed stock had pounced on A.I.G.

“The risk appetite has returned to the marketplace,” he said. “People don’t want to get 5 percent back. They want to get the money back that they lost over the last year.” They look at a cratered stock like A.I.G. and think, “This is the place to do it,” he said.

Taxpayers may take some comfort from the rise in A.I.G.’s stock, which means better returns on their involuntary investment. Even though the government owns most of A.I.G., however, the soaring value of its shares does not come close to matching the vast amount of credit it extended through the Federal Reserve and the Treasury. Roughly $180 billion was marshaled to keep A.I.G. afloat last fall and winter. The entire market value of A.I.G.’s stock is just $6.4 billion, even at the current price.