From CNBC:

Bitcoin took a sharp plunge from over $72,000 to $67,000 in overnight trading, proving its volatility. Despite this, the cryptocurrency is up 57% this year and near record highs. The drop is speculated to be caused by selling pressure from the options market, a healthy correction removing leverage from the system. Bitcoin’s history shows rapid rallies and sharp declines, but with the introduction of bitcoin ETFs, volatility may decrease as the asset class matures.



Read more: Bitcoin shows its volatility once again, tumbling back to $67,000 in overnight decline