Even though all the major stock market rallies since the financial crisis have coincided with new central bank efforts to stimulate the economy, not everyone is buying it.
The latest data shows a moderate increase in short interest - bets that stocks will fall - across S&P 500 stocks during the last two weeks of August, a period when stocks were rallying on expectations of the Fed's announcement. Typically short interest inversely tracks the market. If investors were getting out of bets that stocks will fall, that would mean buying back those stocks and forcing the market higher.
Data provided by Schaeffer's Investment Research, a Cincinnati-based research firm, shows that bets against the biggest 500 U.S. companies edged back to about 7.3 billion shares after falling from about 7.6 billion to 7.2 billion from the start of July through the end of August - a period when the market gained more than 3 percent.
That uptick in short interest could be significant. From the middle of September 2011 through the end of May this year, short interest on S&P 500 stocks fell like a stone to about 6 billion shares. During that period the S&P hit a four-year high, rising more than 20 percent from trough to peak.
One side effect of the Fed's bond-buying should be to reduce volatility in markets. That means the CBOE VIX volatility index should remain close to the five-year lows it hit this summer. In August it fell as low as 13.30.