Answer to: Any explanation for the COVID-19 market surge?

In my mind there are three big reasons for the rise in the US stock market during that time: Interest rate cuts increased the present value of future earnings, and reduced the required rate of return for equities as an alternative investment to bonds, both of which raised equity values at a fundamental level $4.5T in government stimulus artificially driving up demand in the overall economy and, to some extent, investment in stocks. Large companies with online presences benefited significantly more from the lockdowns compared to smaller local stores, which aren't represented in the major stock market indices. As the pandemic wore on, there were supply chain issues which, coupled with lower government stimuli, reduced supply and demand, respectively, causing a slowing of economic growth. The growth curve right now looks very similar to what we saw then, which has me assuming that most or all of my paper gains in the past year will evaporate fairly suddenly a few years from now I can't say that won't happen, but I don't see the same underlying causes for recent growth. I believe that AI had caused both an increase in investment for tech companies and an increase in productivity even in non-tech companies. Whether either or both of those is sustainable is yet to be determined.