Rodolfo Mass, a floor broker at the New York Stock Exchange for almost three decades, has seen the future – and he’s worried.

Just steps away from his spot on the floor, the exchange installed a trading program that enables automation to coexist with face-to-face haggling. The so-called hybrid market is the centerpiece of the NYSE’s transformation into a for-profit company by merging with Archipelago Holdings next week.

“Sometimes speed kills,” Mr. Mass, a managing director at Direct Access Systems LLC in New York, said. “There are going to be less people on this floor in two years’ time.”

The CEO of the NYSE, John Thain, says allowing investors to trade blocks of shares in fractions of a second will hone the Big Board’s edge against all electronic rivals such as the Nasdaq Stock Market.

For the 3,000 brokers and clerks who flock each day to the world’s biggest stock exchange, it’s the biggest technological overhaul since fully automated trading started 30 years ago.

The NYSE, whose share of trading in its listed stocks has fallen to a three decade low, has little choice but to encourage use of computers. By the end of June, the exchange must comply with Regulation NMS, a U.S. Securities and Exchange Commission rule requiring brokers to send orders to the exchange that can execute them automatically at the best price.

Mr. Thain is under pressure from institutional investors to speed trade execution and improve transparency as well. The NYSE’s seven specialist firms, whose employees match buy and sell orders on the floor, paid $247 million in 2004 to settle regulatory claims that they profited at customers’ expense.

Under the hybrid system, floor brokers have the option of completing trades through specialists or routing them through the NYSE’s Direct Plus, a five-year-old electronic system that handles about 14% of trades. The exchange plans to scrap limits on Direct Plus that bars orders exceeding 1,099 shares or coming less than 30 seconds apart.

To test the system, the exchange upgraded software in brokers’ hand-held computers and started a 168-stock pilot program in December.

Trading posts that are marked with six-inch-long green plates reading “e-Quote,” like the one near Mr. Mass, now dot the floor. Brokers approach the post, punch a few keys, and make a wireless trade that sidesteps the specialists and hides larger orders from their competitors.

“They are bringing poker back in the game,” said Andrew Frankel, co-president of Stuart Frankel & Co., an NYSE brokerage for 35 years. “We are very bullish on the plan for hybrid.”

The pilot has been successful so far, said Louis Pastina, the exchange’s senior vice president responsible for the hybrid market. Brokers are averaging about 375 e-Quote trades a day, up from 200 two weeks ago, according to the NYSE. The pilot runs through March.

All told, the NYSE will write a million lines of code for 60 computer systems to implement hybrid trading and to automate many of the specialists’ tasks, he said. The exchange refuses to say how much it cost.

“The specialists have really been at a disadvantage because their method of responding is by punching keys on a keyboard,” said Mr. Pastina, a 22-year veteran of the Big Board. He estimated that all of the specialists combined enter 40 million keystrokes a day, or as many as three per second per person.

“That’s a very difficult model to continue to grow.”