NEW YORK -- Japan's Mitsubishi UFJ Financial Group is investing $9 billion in Morgan Stanley for a 21 percent stake in the U.S. investment bank. Mitsubishi UFJ said it will buy nearly 10 percent of Morgan Stanley's common stock for $3 billion, and $6 billion in preferred stock. Morgan Stanley, along with Goldman Sachs Group Inc., had been one of the two remaining independent Wall Street investment banks until the two recently applied to become commercial banks that take deposits.