There's a lot to be said for the "sell in May" theory, the old Wall Street maxim that predicts stocks will sink from mid-spring through fall, and then outperform the rest of the year.
But some strategists expect this year to be different, despite what seems to be a growing list of red flags, and investors could miss out if they sit on the sidelines.
A pending Federal Reserve rate hike, shaky economic data and mixed corporate earnings all loom as potential negatives for stocks. Yet, a number of strategists expect the S&P 500 to break out after resolving a 2,120 level of resistance, surpassed Monday morning.
"(Sell in May) does usually work if the kind of environment is suggestive that it would," said Ari Wald, technical strategist at Oppenheimer Asset Management. "You'd have weakness going into it, when breadth is weaker as well. What we're seeing in more critical indicators suggests you might not get it."