There appears to be a correlation between the U.S. NFIB Business Optimism Index (USBOI) and the S&P 500. When the Stochastic RSI of the USBOI was oversold to the 2.67 level, the S&P 500 tended to outperform thereafter. Interestingly enough, this signal is currently oversold at that level meaning the S&P 500 could rebound soon.