In general, my experience is that sharp moves up or down over a day or a few days proceed from investors that are reacting, not thinking. Those moves tend to get erased by future market action.
Slower, intermediate-term moves tend to persist, and those moves don’t get the same media attention, because they aren’t dramatic. Bear market rallies are sharp, so are Bull market panics.
That’s why I don’t make too much out of days like yesterday. A news-driven market is over-reactive. Days where there is no no significant news gives us a feel for how the large players are adjusting their exposure; the same is true of looking at the trend over 6-12 months, where the effect of short-term news gets washed out.
So be wary, skeptical, etc., and keep some cash on hand to buy up future bargains.