Equity trading volume continues to plummet

The year-to-date run-up in the S&P 500 continues to be supported by declining trading volumes. Uncertainty about fiscal and monetary policy decisions have left many investors on the sidelines - through the first 13 trading days of August, S&P 500 trading volume is down more than 60% through the same time a year earlier. Average monthly trading volume has been declining steadily since March 2009, when it peaked at nearly 28 billion shares.