Another week, another Wall Street scandal, and another opportunity for pundits to bemoan the incompetence and venality of America’s financial professionals. Last Wednesday’s near collapse of Knight Capital Partners – in which a bug in one of its high-frequency trading algorithms caused the firm too loose $440 million – has raised concerns about high frequency trading and what the practice means for the safety and trustworthiness of our financial markets. But what is high-frequency trading, and is it really all that dangerous?
High frequency trading is a catch-all term that describes the practice of firms using high-powered computers to execute trades at very fast speeds – sometimes thousands or millions of trades per second. These systems have developed over the past ten years, and began to really dominate Wall Street over the last five. For example, a high-frequency trader might try to take advantage of miniscule differences in prices between securities offered on different exchanges: ABC stock could be offered for one price in New York and for a slightly higher price in London. With a high-powered computer and an “algorithm,” a trader could buy the cheap stock and sell the expensive one almost simultaneously, making an almost risk-free profit for himself.