The stock market rally off the early-February lows has created an unusual condition that could be a concern over the next month or so.
More than three-quarters of the S&P 500 components have moved into "overbought" territory, meaning that they are more than one standard deviation away from their 50-day moving average, according to Bespoke Investment Group.
The move comes as the index had gained as much as 14 percent from the Feb. 11 intraday low and could help explain why the market has pulled back some in recent days, falling nearly 1 percent in the holiday-shortened week. Sharp declines in energy, financials and materials have led the move lower.
Along with the gains, professional investors have become strongly optimistic, another contrarian factor that could be contributing to the recent downturn.