Well, the original article makes a claim that this was caused by a margin call feedback loop (thanks pash for finding the right term and some analysis).
There could be other causes. It's hard to untangle whether BitFinex caused the other exchanges to drop, or if it just dropped faster due to margin but had no real effect on the other exchanges.
There could be other causes. It's hard to untangle whether BitFinex caused the other exchanges to drop, or if it just dropped faster due to margin but had no real effect on the other exchanges.