The effects of randomizing the opening time on the performance of a stock market under stress

► Many stock exchanges have switched from a fixed to a random opening time. ► We study how this affected the price discovery process on Tel Aviv Stock Exchange. ► Randomization improved price discovery, especially on derivatives expiration dates. ► Randomization reduced excess volatility and distortion of opening stock prices. ► A random opening time is an effective way to deal with derivatives and illiquidity.