Teenager used an early dealer network to arbitrage sports cards

At 14 or 15, the trader connected with dealers across the U.S. and Canada through an early bulletin board, and was one of the few people in Texas in that network. Because card prices changed week to week, knowing what a product was worth in New York made it possible to buy cards more cheaply elsewhere and send them there for a profit.

The trader said sports cards then felt like commodities, and that tracking product values remained a skill throughout a trading career. At 27, the trader started a firm, hired people and put most of their capital at risk.