Richard Grasso's (search) ability to combine the New York Stock Exchange's 200 years of tradition with the age of automated trading may have been his greatest feat, a balancing act that preserved the screams and shouts that define the exchange.

Now the NYSE's centuries-old tradition of open outcry trade could be under threat again from the low murmur and hum of the digital age.

Grasso, pushed out of his job as the exchange's chairman, championed the traditional system in the face of competition from Archipelago (search), Instinet (search) and other electronic communications networks, or ECNs, that won popularity in the mid 1990s. Instinet Group Inc. (INET) is majority owned by Reuters Group Plc. (RTRSY

Grabbing market share from both the NYSE and Nasdaq, ECNs argued that largely anonymous automated trading is the most efficient and cost effective way of doing business.

Grasso acted aggressively to stem their encroachment, but it remains to be seen whether his successor will have the political savvy or the iron will to follow suit.

Historically, the NYSE has not been a big fan of change. After all, for the last century it has been run from the same, drafty neoclassical building. Even a state-of-the-art trading room built as a nod to the sleek "New Economy" of the 1990s performs essentially the same functions as the older trading rooms.

And while it invested millions of dollars in new technologies to improve order flow, speed and buy/sell matching, it nonetheless preserved the open-outcry, auction trading model. Indeed, the NYSE's method is as old as the exchange itself, established in 1792 under a buttonwood tree on Wall Street.

But when Grasso slipped out of the NYSE Wednesday, little doubt was left that significant change is coming — both upstairs on the fortified, ornate sixth floor, and downstairs on a trading floor that is a daily scene of raucous commerce.

"What would appear to be old fashioned isn't," said veteran NYSE specialist trader James MaGuire Sr. of LaBranche & Co. (LAB) "For people to say 'move electronically.' Well, my goodness, we've done that, we're there."

But the lifeblood of the NYSE is still the thousands of traders who scream and shout while carrying out stock sales, even as computers that match buyers and sellers have replaced people on the floor of competing exchanges.

There are many who would like to keep it that way, particularly the specialists, floor brokers and the firms that employ them. Grasso, ousted over outrage about his $140 million pay package, supported the old system, saying people are required elements of any efficient trade.

Grasso and others argued that only an experienced trader can gauge the nuances of supply and demand for any given stock at any given time, and trade to exploit these subtle shifts.

MaGuire, whose firm LaBranche is among the top specialist firms, believes investors don't want to see the exchange do away with its floor specialists and brokers.

"They want point-of-sale representation," he said on a windy Thursday morning outside of the NYSE. "Until they develop some pretty sophisticated robots, we'll be there."

Whether the new NYSE leadership will agree is unclear, but critics have not softened their stance.

"The difference between us and open outcry is immediacy, consistency and certainty. You know exactly what the rules are, because they are hard-coded into the software," said Jerry Putnam, chief executive of Archipelago.

In the meantime, as the NYSE board of directors draws up a short list of candidates for chairman, the traders and brokers who Grasso protected have tried to get back to business.

With their green badges, they passed through security that Grasso beefed up after the attacks of Sept 11, while others sat on the steps of neighboring buildings, sipping coffee, smoking cigarettes and scanning the tabloids for clever, Grasso-inspired headlines.

"It's going to be different," said one. "I just don't know..."