COVID-19 vaccines and global stock markets

•Global stock markets react positively when clinical trials of COVID-19 vaccines begin.•The market’ reaction is stronger for leading vaccines and phase III trials.•Progress of vaccines developed in the U.S. or China is more appealing to the market.•Market-wide expectation of vaccine development is conveyed by stock markets. Global stock markets react positively when different phases of human clinical trials on COVID-19 vaccines begin. The average abnormal stock return on the first day of the trials is both statistically and economically significant at 8.08 basis points. The increase in the average abnormal stock return is threefold higher for leading vaccine candidates. The positive reaction is more pronounced upon the start of phase III trials, and it is also stronger for vaccine candidates developed by the U.S. and China.