NEW YORK (CNN/Money) - John Thain rose quickly through the ranks at Goldman Sachs to eventually take the No. 2 spot at the firm and some on Wall Street saw him in line for the top job at the investment bank rather than as CEO of the world's largest stock exchange.

Thain, who has a undergraduate degree from MIT and a master's in business administration from Harvard, was named sole chief operating officer a few months ago. He also served as president of the company.

In 1999, when former CEO Jon Corzine left the firm, Thain became president and co-chief operating officer, until the departure in March of his counterpart, John Thornton, which left Thain first in the line of succession for the top spot at Goldman.

While Thain rose quickly through the firm's upper ranks, he differed from the company's stance when it came to the New York Stock Exchange.

John Thain's rise through Goldman Year  Position  1994-1999  CFO, head of tech., finance operations  1995-1997  Co-CEO of European operations  1998  Named director  1999  President, co-COO, Goldman Sachs Group, L.P.  1999-June 2003  President, co-COO Goldman Sachs Inc. July 2003-Dec. 2003  President, COO, Goldman Sachs Inc.   Source: Goldman Sachs

In a Nov. 20 investor conference held by Merrill Lynch, Thain told the audience the NYSE should look to more electronic trading that would bypass the exchange's specialist system, especially with trades that match in price and size, according to the Wall Street Journal. Specialists' job is to match investors' orders to buy stocks with orders to sell them.

An option Thain, 48, suggested would be to allow customers to choose how they want their trade orders executed: either best price with the current system on the NYSE, or with best speed through an electronic trading system.

After making his comments, the paper reported, Thain told the audience the views he expressed were his own and probably weren't in agreement with some of his colleagues at Goldman Sachs, which owns Spear, Leeds & Kellogg, the second-largest specialist firm on the New York Stock Exchange. Until it bought Spear Leeds in 2000, Goldman was a leading advocate of electronic trading.

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"Those comments at the Merrill conference were important because it really showed what [Thain's] vision of the exchange is," said Reilly Tierney, analyst with Fox-Pitt, Kelton. "He was known as an advocate of technology at Goldman and his comments at Merrill were really not a surprise."

But at his appointment press conference Thursday, Thain was quick to reassure the specialist firms, saying that "it's very important the exchange's specialists retain their role."

Interim NYSE CEO John Reed said at a press conference Thursday he has known Thain for about five years and both serve on the graduate school board at MIT.

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Lloyd Blankfein, head of Goldman's currency, fixed income and commodities operations, will replace Thain as the company's president and COO.

"It's always a negative when you lose a top executive and [Thain] was widely seen as a successor to [Goldman CEO Henry] Paulson," Tierney added. "But Paulson is not leaving anytime soon, so it's not an immediate issue. Blankfein is also very capable."

The $4 million annual pay package Thain will receive at the NYSE will be a big step down from his days at Goldman. In 2002, Thain received a salary of $600,000, a bonus of $5.8 million and restricted stock worth $2.3 million. In 2001, he earned a salary of $600,000 and $10 million bonus, but no restricted stock, according to Goldman's proxy filing. At the current Goldman stock price, Thain's holdings are worth more than $300 million.