Martin T. Sosnoff, the New York investment adviser whose Atalanta Capital Corp. has acquired control of 9.32 percent of the publicly traded stock of The New York Times Co., is a freewheeling, irreverent professional money manager who, by his own account, has made and lost fortunes in stock speculation over the past 20 years.

According to his memoirs, he grew up poor in the Bronx, got his view of the Ivy League from vendors' booths outside the football stadiums, and is still "as insecure today as when I first came to Wall Street in a seersucker suit with a yellowed collar."

Sosnoff has a reputation--which he honed in several years as an occasional columnist for Forbes magazine--as a shrewd, hard-nosed investor who disdains the conventional methods of Wall Street analysis. In his view, "the day of the intelligent investor is gone . . . the name of the game is guerrilla warfare."

He is also a longtime associate of Saul Steinberg, the controversial financier who sold his own block of Times stock just as Atalanta was buying $37 million worth of Times shares last month. He has known Steinberg for a decade, since Steinberg was the boy wonder of Wall Street with his Leasco computer-leasing company. Sosnoff has evidently made and lost millions in the stock fluctuations of Leasco and Steinberg's Reliance Financial Group, which he praised as investments in his Forbes columns.

Charles Persell, assistant counsel of Reliance Financial, said he had "no way of knowing" if the stock sold by Steinberg was part of the block bought by Sosnoff the same day, Feb. 17. Richard Weinberg, Sosnoff's attorney, declined to comment on any possible connection between the two transactions, and said his "no comment" did not imply that he even knew the answer.

Times officials, who made no secret of their discomfort at having the flamboyant Steinberg as the company's major outside stockholder, have said nothing publicly about the entry of Sosnoff into the company with an even larger stake than Steinberg held.

"There's more to find out about this, and we expect to," a senior Times official said.

The Times corporation is so structured that no outsider could obtain control of the company, even by acquiring all publicly traded Class A shares. Under an irrevocable long-term trust, members of the Sulzberger and Ochs families and other insiders hold the Class B stock, unlisted and seldom traded, which elects 70 percent of the directors and has unlimited voting rights.

Atalanta, of which Sosnoff is chairman of the board, said in papers filed with the Securities and Exchange Commission that it acquired the Times stock "solely for investment purposes" and did not expect to acquire any more or seek any changes in Times management.

That left unanswered the question of why a canny Wall Street veteran such as Sosnoff should pick the Times, of all stocks, in which to invest $6 million of his personal funds and another $31 million put up by unnamed clients, just as Reliance--which Steinberg took private by buying out the other stockholders in January--was unloading most of its 5.28 percent of Times shares.

Steinberg and Sosnoff were codefendants in a recent stock-fraud suit in federal court in Los Angeles, involving allegations that they made false representations to obtain Leasco stock from others. Judge Thomas Takasugi dismissed the case against Steinberg, but the case against Sosnoff is still pending and could, according to Atalanta's filing with the SEC, "result in a finding of violation of federal or state securities laws."

Most of what is known about Sosnoff comes from his brash, often vulgar memoir, "Humble on Wall Street," published in 1975. In the book, Sosnoff recounts how he got rich in the 1960s trading stocks disdained by others as "ragamuffins."