Maurice R. Greenberg, who built the American International Group into an insurance behemoth with an impenetrable maze of on- and offshore companies, is at it again.

Maurice R. Greenberg, the former head of A.I.G., on his way to court in Manhattan last June.

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Even as he has been lambasting the government for its handling of A.I.G. after its near collapse, Mr. Greenberg has been quietly building up a family of insurance companies that could compete with A.I.G. To fill the ranks of his venture, C.V. Starr & Company, he has been hiring some people he once employed.

Now, Mr. Greenberg may have received some unintended assistance from the United States Treasury. Just last week, the Treasury severely limited pay at A.I.G....