Society's techno-social systems are becoming ever faster and
more computer-orientated. However, far from simply generating faster versions
of existing behaviour, we show that this speed-up can generate a new
behavioural regime as humans lose the ability to intervene in real time.
Analyzing millisecond-scale data for the world's largest and most powerful
techno-social system, the global financial market, we uncover an abrupt
transition to a new all-machine phase characterized by large numbers of
subsecond extreme events. The proliferation of these subsecond events shows an
intriguing correlation with the onset of the system-wide financial collapse in
2008. Our findings are consistent with an emerging ecology of competitive
machines featuring ‘crowds’ of predatory algorithms, and highlight the need for
a new scientific theory of subsecond financial phenomena.