ETF volumes have really taken off

After rising more or less in line with overall market volume for years, there has been a noticeable surge since the spring in the relative turnover of selected exchange-traded funds (ETFs).

For the SPDR Trust Series 1 ETF (AMEX: SPY), which tracks the S&P 500 index, the average daily volume (ADV) compared to New York Stock Exchange Composite ADV increased from 6.1% in April to 16.8% last month. For the PowerShares QQQ ETF (NASDAQ: QQQQ), which emulates the Nasdaq-100 index, the numbers went from 6.3% to 14.1%. For the iShares Russell 2000 Index Fund ETF (AMEX: IWM), which mirrors the small cap benchmark, relative turnover rose from 3.4% to 6.7%.

Although it's not clear whether the activity was related to hedging or outright position-taking -- or both -- the sharp increase in activity suggests that there has been an important change in the underlying dynamic of the U.S. equity market. If so, it raises some interesting questions.

Could this be a sign, for example, that the influence of hedge funds, proprietary trading desks, and other speculative operators is expanding dramatically? Are investors of all stripes becoming increasingly focused on ETFs as an investing vehicle? Does this emphasis on trading bundles of shares mean that more individual issues are "mispriced"?

Whatever the case, this is a trend worth paying attention to.

Michael Panzner is a 25-year veteran of the global stock, bond, and currency markets and the author of Financial Armageddon: Protecting Your Future from Four Impending Catastrophes and The New Laws of the Stock Market Jungle.