Textbooks have nothing to do with reality of the markets. Those who believe in EMH - please check out what happened to price of Zoom in March 2020.
However, the stock price of Zoom Technologies Inc (stock ticker ZTNO, but at the time ZOOM), a completely unrelated company based in China, went up by something like 1000%, due to what is generally believed to be uninformed day traders who saw "Zoom Technologies" and assumed it was the videoconferencing company.