“It’s remarkable what they can do,” said Blair Hull, a founder of an electronic trading firm who relies on Jane Street to make a market for his recently started E.T.F. “If you look at who provides this kind of liquidity these days, it’s fewer and fewer firms.”

It is not only Jane Street, of course. Cantor Fitzgerald, the Knight Capital Group and the Susquehanna International Group have all capitalized on the E.T.F. explosion.

And as these firms have grown, so has the demand for a new breed of Wall Street trader — one who can build financial models and write computer code but who also has the guts to spot a market anomaly and bet big with the firm’s capital.

In a word, these are not your suit-and-tie bond and stock traders of yore, riding the commuter train into Manhattan. They are, instead, the pick of the global brain crop.

Here is a small sample of Jane Street’s main traders: Tao Wang (doctorate in philosophy and finance from the National University of Singapore), Min Zhu (master’s in chemistry, Columbia), Brett Harrison (master’s in computer science with a focus in artificial intelligence, Harvard) and Srihari Seshadri (bachelor’s in computer science, Carnegie Mellon).

For large asset management firms like BlackRock, Vanguard and Invesco, the business of rolling out one E.T.F. after another has become a major profit center. But in many ways, the real money is being made by the trading firms that specialize in making a market in these securities.