Who's Who: The Players Remaking Wall St.

The financial world has been rocked to its foundations in a few short days, with a handful of men making momentous decisions. The Wall Street Journal outlines the key players.

• Henry Paulson. No Treasury chief has wielded such power. He decides whether big firms live or die via federal bailouts. Will his too-big-to-fail philosophy stand the test of time?
• John Thain. The Merrill Lynch CEO saw the writing on the wall for his own firm while working on the Lehman crisis. In less than 24 hours, he hammered out a deal to sell Merrill to Bank of America.

• Kenneth D. Lewis. The Bank of America chief's bold buy of Merrill lifted BoA as its rivals crumbled around it.
• Robert E. Diamond Jr. The Barclays boss backed out of a deal to buy Lehmans after the government and Wall Street refused support, but he bought the best bit of Lehman after the bankruptcy.
• Richard Fuld. The Lehman chief had the most to lose and he lost it. Filings show Fuld, once famed for his golden touch, sold 2 million Lehman shares for $525,000 Monday. They would have fetched $145 million in January.

(More Henry Paulson stories.)