At the turn of the millennium, when an investment fund manager in Manhattan or the City of London wanted to trade on market-moving information, the process was as artisanal as it was agonizingly slow: armies of junior research analysts rushed to scan physical press newswires, highlighted 200-page SEC 10-K filings with marker pens, and placed frantic phone calls to equity brokers to adjust their portfolios. In that analog Wall Street dominated by human gut instinct and locker-room rumors, virt...