When developers at a top U.S. stock exchange needed help debugging a program that puts time stamps on quotes and trades in July, they could have hired a high-profile consulting firm. Instead, they called a customer who runs a company out of a small office in a Chicago suburb who had weeks earlier called the exchange’s dealings with high-frequency trading firms “completely illegal” on Twitter. The customer, Eric Scott Hunsader, and a colleague did the work in a few days — for free. Hunsader occupies an unusual position in the investing world. Founder of a software company called Nanex, he is a market data expert whose tools for ...
