One of the big measures of risks is the VIX indicator. As we can see from the chart from Bespoke, the down trending VIX correlates inversely with the S&P 500, not 1 to 1 but close enough to be interesting. This lends weight to another factor girding the underlying bull run.
While one measure of volatility recently made a new short-term low, the VIX volatility index recently failed to take out its recent lows and is now trading back above 30 even when the overall market has made new short-term highs. This failure to head lower has some investors looking for a pause in the rally, as fear of a pullback seems to be creeping back into the market.
p/s photo: Angelababy Yang Wing