At a certain point, this quest for edge inevitably bumps up against, and then crosses, a line: advance knowledge of a company’s earnings, word that a chipmaker will get a takeover offer next week, an early look at drug trial results. This kind of information—proprietary, nonpublic, and certain to move markets—is known on Wall Street as “black edge,” and it’s the most valuable information of all. Trading on it is also usually illegal.
