In speeches, Ms. Schapiro has also raised the idea of limiting the speed at which machines can trade, or requiring high-frequency traders to stay in markets as buyers or sellers even in volatile conditions. just as human market makers often did on the floor of the New York Stock Exchange. .

“The emergence of multiple trading venues that offer investors the benefits of greater competition also has made our market structure more complex,” she said in Senate testimony last month, adding, “We should not attempt to turn the clock back to the days of trading crowds on exchange floors.”

MOST of the exchanges have already eliminated a controversial electronic trading technique known as flash orders, which allow traders’ computers to peek at other investors’ orders a tiny fraction of a second before they are sent to the wider marketplace. Direct Edge, however, still offers a version of this service.

The futures trading commission is considering how to regulate data centers, and the practice of co-location. The regulators are also examining the implications of so-called dark pools, another product of the technological revolution, in which large blocks of shares are traded electronically and without the scrutiny exercised on public markets. Their very name raises questions about the transparency of markets. About 30 percent of domestic equities are traded on these and other “unlit” venues, the S.E.C. says.

For Mr. O’Brien, the benefits of technology are clear. “One thing has surprised me: people have looked at this as a bad thing,” he says. “There is almost no other industry where people say we need less technology. Fifteen years ago, trades took much longer to execute and were much more expensive by any measure” because market power was more concentrated in a few large firms. “Now someone can execute a trade from their mobile from anywhere on the planet. That seems to me like a market that is fairer.”

For others who work at the company or elsewhere in the financial ecosystem of New Jersey, it has been a boon.

“A lot of my friends work here or in this area,” says Andrei Girenkov, 28, one of Direct Edge’s chief programmers, over lunch recently in Dorrian’s restaurant in Direct Edge’s building. “It changed my life.”