On Saturday afternoon, in his vault-like office just two blocks from Wall Street, Tim Geithner, the New York Federal Reserve President, was listening to a heartfelt protest from John Mack, chief executive of Morgan Stanley.

Why, he asked Mr Geithner and Henry Paulson, the US Treasury Secretary, should he help to bail out Lehman Brothers? Why was he being picked on, when the likes of hedge funds and pension funds were not? And if he and the other investment bankers who were assembled in the room did bankroll a rescue deal for his smaller competitor, where would it end? Would they have to bail out another bank, perhaps Merrill Lynch?

Mr Mack could not have imagined that just five days later his own bank, Morgan Stanley, would be the subject of most anxiety on Wall Street.

Mr Mack is not used to being a victim. On his long slog to the top of Wall Street, he became known for rallying his staff to seize new business by shouting: “There’s blood in the water, let’s go kill.” He was notorious for holding shouting matches on trading floors and being obsessed with costs.

The son of Lebanese parents, Mr Mack was born John Machoul, but his father, a small-time retailer in North Carolina, changed the family name. Mr Mack cut his teeth in business while studying history at Duke University, on an American football scholarship, running an after-hours snack-joint from his dorm.

He graduated in 1968 and joined Morgan Stanley as a bond trader in 1972. It would take him 21 years to rise to become president of the bank.

Mr Mack met his match when he lost a leadership fight for the bank with Philip Purcell. He quit the bank and joined CSFB as chief executive, charged with cutting spending and improving the bank’s tarnished image. Within a couple of years, he had sacked 10,000 bankers, cut $3 billion from costs and abolished some of the more egregious perks, earning him the nickname “Mack the Knife”.

Mr Mack coaxed, bullied, and charmed bankers to take pay cuts for the good of the bank. He flew across the country to persuade Frank Quattrone, then the star of CSFB, to rip up his contract and agree to new pay terms. Mr Quattrone agreed and was rewarded with a seat on the board. On another occasion, Mr Mack arranged for the famous coach of the Duke basketball team to telephone one CSFB banker, a fan, to thank him on Mr Mack’s behalf for paying back $50 million of remuneration to the bank. By turning away business where there were obvious conflicts of interest, he also helped to improve the bank’s ethical reputation. Mr Mack later said that turning round CSFB got “my blood pumping”.

Five years after leaving Morgan Stanley, after Mr Purcell was ousted, Mr Mack made a triumphant return, aged 61. Since then, he has been driven by trying to compete with his arch-rival, Goldman Sachs.

As Mr Mack seeks to secure a deal with Wachovia, the mortgage bank, he is effectively returning to his roots. The retail bank which he hoped will help to cushion Morgan Stanley, has its headquarters in Charlotte, North Carolina, just 30 miles from Mooresville, the town where he grew up.

Few introductions were required between chief executives of the two banks – Mr Mack attended Duke University with Robert Steel, his opposite number at Wachovia and both have been on the college’s trustees for more than a decade.

While other financiers, such as Hank Greenberg, the former chief executive of AIG, have complained that this week’s losses on Wall Street have wiped out their net worth, the same is unlikely to be the case with Mr Mack. His bonus in 2006 alone reached $40 million, adding a little to a mountain of wealth accumulated from a life in investment banking.

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