Money Dow, S&P 500 keep falling. So how will we know when the stock market drop is over? March 18, 2020March 18, 2020 Adam Shell, Special to USA TODAY Comments Off on Dow, S&P 500 keep falling. So how will we know when the stock market drop is over? The coronavirus pandemic is sending the Dow and S&P 500 spiraling lower. So what are some signs that the stock market plunge could end?