The S&P 500 dropped 1.1% in the past five days for the worst week since mid-December. In fact, the S&P 500 has risen an average of 0.45% on the day after a fall, a stronger rebound than any year since 1928. Consider the renowned 50% retracement indicator that is often touted as a nearly foolproof signal that a rally has legs. At a closing high of 4,180 on Feb. 2, the S&P 500 erased half of its peak-to-trough decline incurred during the last year. In many ways, the rally that lifted the S&P 500 as much as 17% from its October trough has been at odds with a worsening fundamental story.