To a few Wall Street financiers, a lawsuit that accuses the government of shortchanging the American International Group in its 2008 bailout is something else: a promising investment in a cause they support, the New York Times reported today. Maurice R. Greenberg, the former AIG chief executive who still holds a large stake in the insurance company, filed the lawsuit on behalf of fellow shareholders. He has now raised several million dollars from three Wall Street companions to help cover the cost of the case. The investors, who are entitled to a cut of any damages Greenberg collects from the government, contributed about 15 percent of the tens of millions of dollars in legal costs. Six years after the government saved Wall Street from the brink of collapse, the lawsuit is coming to trial, reopening one of the ugliest chapters in modern financial history. The trial, which begins next week in Washington, D.C., will most likely hinge on testimony from the policy makers who orchestrated AIG’s rescue, including former Federal Reserve Chairman Ben S. Bernanke and former Treasury Secretary Timothy F. Geithner.