Accordingly, Mr. Epstein, who lives and works on a private island in the Virgin Islands but maintains an office in New York, does not stint in compensating them. In addition to the rich payday, he also ladles on the perks: he maintains a charge account at Frédéric Fekkai, the society hair dresser, for their unlimited use and pays for all food eaten during his lengthy business hours, including takeout from Le Cirque. On trips on his Boeing 727, he frequently takes two of the assistants with him.

When one of them, Lesley Groff, who is 38, became pregnant last year and talked of leaving, he bought her a Mercedes-Benz E320 to make her commuting easier and agreed to pay for a full-time nanny so that she could keep working for him.

"There is no way that I could lose Lesley to motherhood," said Mr. Epstein, who is in his early 50's and is a bachelor.

There are those on Wall Street who feel that it is hard to attach a true value to such people.

"They know everything and they eventually take over," said Michael M. Thomas, a former Lehman Brothers partner. Mr. Thomas retained his assistant for 16 years and as a child he remembers receiving personal letters from his father, also a financial executive, that were signed by his secretary. "You are paying for loyalty as well as indispensability. Grasso took home $139 million and he paid the keeper of his secrets a quarter million. That is a very small economy."

In Mr. Grasso's case, his assistant remained loyal to him. According to lawyers close to the case, the assistant, SooJee Lee, 38, was reticent about her boss when she was interviewed by stock exchange lawyers as they compiled a report on Mr. Grasso's pay, which totaled $192.9 million in compensation and paid pension benefits in his eight years as chief executive.

Their conclusions, released this week in what is known as the Webb report, noted that comparing the pay of Mr. Grasso as chairman of a self-regulated institution with that of the chief executives of big Wall Street firms was inappropriate; the report said he received $144 million to $156 million in excessive compensation.

In many ways the role of the assistant as omnipotent gatekeeper has evolved in recent years as the corporate conduct of chief executives has become a target for regulators. A number of chief executives of Wall Street firms shun e-mail these days, not because they are Luddites, but because e-mail messages have ended up as evidence in cases brought by regulators. Now, to send e-mail messages to these men, one has to send a message to his assistant.