We studied the intraday effects of return overreactions around extreme negative one-minute interval returns of Nasdaq100 constituents based on nanosecond data. An extreme negative one-minute interval return is defined as the lowest return that occurs once in 1,000 one-minute intervals. We document that 31% of such an extreme one-minute interval's return is reversed in the subsequent trading minute. The relative magnitude of the reversal after extreme negative one-minute interval returns is particularly high for the 20% most liquid and the 20% largest firms of our sample.