After the conference call to his employees, after he briefed the stock analysts and the media and watched Wall Street exult over the prospect of Legg Mason Inc. morphing into the world's fifth-largest money manager, Raymond A. "Chip" Mason sat down and pondered the hard part, which hasn't happened yet.

The new clients must stay happy, he said. They have to trust that shifting their investments from Citigroup Inc., the largest financial services firm on the planet, to a home-grown operation in Baltimore will be seamless. It's the riskiest element of Legg Mason's deal, in which it will shed the brokerage business upon which it was founded and acquire Citigroup's money management business, Mason said.

"I have no idea if this bridge is a real bridge or not," Mason said. "And I'm walking across this ravine."

Yet there's a safety net, installed at the demand of other executives who negotiated the $3.7 billion deal. Chip Mason is it.

The 68-year-old chief executive will work at least two more years from his office atop the Legg Mason tower on Light Street, carrying out the deal that will leave his company managing some $830 billion in investors' money. The gray-haired engine behind Legg Mason's extraordinary growth preached about ethics before it was vogue and rooted out conflicts of interest before it was law. Such is his reputation for dependable and respectable oversight, analysts say if he weren't staying the deal might not survive.

Mason's insistence that brokers and asset managers not commingle was considered stodgy back before such things spawned industry scandals, they say. His line about employees never getting close enough to ethical lines to even get chalk on their shoes sometimes seemed tired. But as Legg Mason stands to become an international powerhouse in the business of managing mutual funds and bond portfolios, the prescience of the firm's surviving namesake seems apparent.

"I know it sounds kind of breathless, but in his case I think it's true. He was a visionary," said Ben Phillips, managing director of Cerulli Associates, a financial services consulting firm in Boston. "He realized, when it now seems like no one else did, that brokers and asset managers have different skills - that if you kept them autonomous they were better equipped to succeed. Well, today everyone knows he was right."

Mason wasn't cheering Friday. Associates said he seemed more relaxed than normal after the deal's announcement, perhaps relieved to have the marathon negotiations behind him. But as he sat for a moment to discuss the deal, in the glow of his office's postcard view of the city, he was cautious about sounding gleeful. There would be no pictures taken down on the company's trading floor, where brokerage employees were still assessing their fates. "It's too soon," he said.

So wrenching was the decision to trade away Legg Mason's brokerage - an evolved version of the trading operation Mason & Co. that he founded in Newport News, Va., in 1962, at age 25 - that it nearly scuttled the deal, he said. One reason the negotiations dragged on, why the company didn't announce the deal for weeks even after details leaked to the media, was his emotional attachment to the business that was his life for so long.

"I would get cold feet and say, 'I can't do this,'" he said. "To call it traumatic is an understatement.

"This is something that I've built for the last 40 years, and for me to more or less say, 'I'm walking away'? It was not easy. It's where I started."

Still, he and others say they knew the deal was inevitable - if not with Citigroup, then with one of the countless other firms that have knocked on his door in recent years. And the roots of that impending future can be traced at least back to 1986, when Legg Mason acquired the Los Angeles-based bond firm Western Asset Management Co., getting one of its first tastes of a business where revenue doesn't rise and fall on the market's whims.

The brokerage was still Legg Mason's main business - as it was in 1970 when Mason merged with Legg & Co., whose Baltimore brokerage business dates to 1899 - but the future had been cast.

The asset-management business grew precipitously in the years that followed, accounting for 33 percent of the company by 1995. Then Legg Mason went on a buying bender - Brandywine Asset Management, Perigee Inc., Private Capital Management, Royce & Associates, among others - and its managed assets skyrocketed. By 2004, asset management was 69 percent of Legg Mason's business.

The growth and acquisitions garnered some attention from the industry's observers, but so did another remarkable development: Executives at the acquired companies tended not to leave. And when they investigated why, they often found the same answer: Chip Mason.

"When he goes out to acquire ... people can pick up the telephone and call these other firms that have been acquired, and they say, 'This is a good person to deal with.' That is critical," said George A. Roche, chairman and president of Legg's cross-town competitor, T. Rowe Price Group, in a recent interview. "When people sell out to Legg Mason they don't want to just do it for money; they do it because they can continue to work with them and flourish. And they have."

"I have told people for years he is perhaps the best executive in the financial services industry," Roche said.

Mason was born in Lynchburg, Va., in 1936, graduated from the College of William & Mary with a degree in economics in 1959, and founded his brokerage in southeastern Virginia two years later, hiring friends from college. Today he owns more than 3.1 million shares of Legg Mason stock, worth more than $300 million at Friday's closing price, and earns an annual salary and bonus package of roughly $7.6 million, not counting stock options.

In early 2004, Legg Mason settled a case with the Securities and Exchange Commission and the National Association of Securities Dealers in which it was accused of failing to provide certain volume discounts, paying more than $10 million in reimbursements and fines. At a time when the SEC and other federal authorities were investigating alleged in-trading and fraud throughout the industry, the settlement hardly registered. Many other brokerages were similarly penalized.

Also last year, CBS MarketWatch named Mason "CEO of the Year," not just for increasing the company's assets by billions of dollars in a weak investment year but also for "standing above Wall Street's nefarious dealings."

"It's not just marketing propaganda for him, it's a tenet of his management philosophy," said Tal Daley, a Legg Mason senior vice president who briefly left the firm in 1990 but says he quickly returned because of the culture that Mason engendered there.

"It's a big reason I've been here for 22 years."

The remodeled Legg Mason, and the imprint that its top executive continues to have on its character, had people considering the company's future last week.

"It makes me think of two important questions," said Phillips. "Now that Legg Mason is so much bigger, can the same model still work? And maybe most importantly, what happens when Chip decides to step away?"

Mason was wondering the same thing. His arrangement to stay on for two years - "The market has got to believe, in essence, that an old head is sitting there to watch what is going on," he said - means that the company will probably start looking for his successor soon.

He's hoping for someone inside the firm, though he wouldn't offer names.

"My legacy?" he asked. "This will define it. No matter what I've done until now, it won't matter, because of this."

Sun staff writers Bill Atkinson and Laura Smitherman contributed to this article.