Why does Trump and in some instance the public believe the stock market will do worse under Biden? Historically the stock market does about the same to slightly better under Democrats. Obama/Biden have beat Trump on near month to month basis in S&P 500 returns even before the pandemic.
https://www.macrotrends.net/2481/stock-market-performance-by-president
Stocks are grossly overvalued right now anyway. It should not have rebounded after the covid-crash. Trump is really lucky that it is his only saving grace at this point and that Wall Street still has modicum of faith left in him.