Since June 12, the S&P 500 has had five fairly sizable drops. Each time it has dropped it bounced back very strongly the next day. Today is the fifth time this occurred.
This action is a reflection of very strong underlying support. The downside movement fails to gain momentum because there are so many underinvested looking to put capital to work. Dips like yesterday don't scare the bulls but are viewed as buying opportunities.
Sooner or later this pattern will change but patterns have a tendency to persist longer than those that are fighting them think they will. The same arguments as to why this market should drop are still in place and market players are still ignoring. If the market was down today we would be seeing a series of headlines about how an increase in Covid-19 cases is causing a selloff.
What bears seem to not understand about this market is the strength of speculative trading. It may be just small amateurs playing this game but it is a powerful force. This speculative action sucks in pros with big bucks that don't want to miss out on trades that are working. The fact that the stocks may not be investment quality is irrelevant.
My time frames are very short and I'm moving very fast but this is some of the best speculative trading that I've seen since the internet bubble days back in 2000. It won't last and as the bears always say 'it will end badly' but you have to make hay while the sun is shining.