According to sources, the Ethereum flash crash was caused by one monstrous trade. A single $12.5 million dollar sell order triggered auto-trades preset by other traders. This resulted in the immediate crash down to 10 cents. Luckily, as soon as Ethereum hit the 10 cent mark, a multitude of traders immediately placed new orders for the digital currency. This caused a jump back to around $300.
It is currently unclear if margin trading was the culprit, or if Coinbase was culpable for the incident. Regardless, the cryptocurrency and bitcoin markets will continue to generate mainstream regulatory scrutiny, as well as mainstream adoption.