From this analysis emerged records of 18,520 sub-950-millisecond crashes and spikes — far more than they, and perhaps almost anyone, expected. Equally as striking as these events’ frequency was their arrangement: While market behavior tends to rise and fall in patterns that repeat themselves, fractal-style, in periods of days, weeks, months and years, “that only holds down to the time scale at which human stop being able to respond,” said Johnson. “The fractal gets broken.”