Last week’s historic market plunge, in which the Dow Jones Industrial Average fell nearly 1,000 points over the course of a few minutes, has led to increased scrutiny of so-called “high-frequency trading” systems and their effect upon market prices. “High-frequency trading” involves the use of computerized systems to place large amounts of orders that are processed within fractions of a second to exploit minute shifts in the price of securities. A number of electronic trading markets have come under particular scrutiny, including the New York Stock Exchange Euronext and Nasdaq OMX Group. Executives from both of these exchanges are set to meet with the Securities and Exchange Commission today to discuss how “conflicting trading rules” may have contributed to last Thursday’s dramatic decline.