NEW YORK (AP) — The stock market took another nosedive Wednesday as the American banking system appeared even shakier and investors worried that the financial crisis is spinning so far out of control that even government rescues can’t stop it. The Dow Jones industrial average, which only two days earlier had suffered its steepest drop since the days after the Sept. 11 attacks, lost another 450 points. About $700 billion in investments vanished. One day after the Federal Reserve stepped in with an emergency loan to keep American International Group Inc., one of the world’s largest insurers, from going under, Wall Street wondered which companies might be the next to falter.