The former investment bank, now a bank holding company, plots its future.

Morgan Stanley will cut 10 percent of the staff in its biggest business, the institutional securities group, which covers everything from investment banking to stock trading.

John J. Mack got his deal — and, at long last, some relief on Wall Street.

The embattled investment bank Morgan Stanley agreed to give the Japanese bank preferred stock that pays a 10 percent dividend instead of common stock.

The investment in Morgan Stanley by Mitsubishi UFJ Financial Group could be a crucial step in the strategy for revitalizing the American financial system.

Morgan Stanley was racing to secure its financial lifeline from a big Japanese bank as confidence in the embattled Wall Street bank continued to erode.

After another rough day for Morgan Stanley — its stock fell 26 percent, and new doubts arose about a $9 billion infusion from Japan — it seemed Morgan’s chief, John Mack, can’t catch a break.

The bank’s stock price was pushed down by rumors about the fate of a $9 billion injection by the Japanese bank Mitsubishi, illustrating how much Morgan Stanley is exposed.

Mitsubishi will pay $9 billion for 21 percent ownership of Morgan Stanley. The companies also announced a strategic alliance with a focus on corporate and investment banking.

For most of the financiers who remain, with the exception of a few superstars, the days of easy money and supersized bonuses are behind them.