Yesterday's correction happened because of the difference between the S&P500 yields rise compared with the 10-year treasurer yield. The SMI service weakness has spooked investors, and risk is on the rise. The S&P chart also shoes the august bounce back made a lower high than July and broke through the low trend line . The outlook is weak, and the US Fed cut will not stoke the economy underscored by Trumps' recent impeachment scandal
The main reason for the turn around was because the S&P500 yields relative to the ten-year treasury went up above 0.044 %. When ten years treasury dropped to 1.56%, it has triggered a shift of more significant portfolio allocation from the treasury to S&P500 equity that offered a better dividend yield of 2%.