This Chart Shows How Complex the U.S. Stock Market Has Become

In recent years, the U.S. stock market has changed dramatically, thanks to an influx of regulatory, technological, and competitive pressures. The increasing complexity of the market has often been blamed for the technological glitches that appear to be occurring with some frequency on the country's stock exchanges.

On Wednesday, the New York Stock Exchange halted trading for three and a half hours to fix a computer malfunction. While NYSE is one of the biggest U.S. stock-trading venues, it is still just one of 11 exchanges and more than 50 private venues where American equities change hands. As Bloomberg News reported, while today’s issue affected transactions on NYSE's main market, and indexes derived from prices generated by that venue, investors could still buy and sell stock elsewhere.