It is worth noting, that the financial markets are experiencing a strong decline today as well. Obviously if money is fleeing classical markets, the cryptocurrencies - volatile as they knowingly are - will take a big hit as well. Just saying.
Looks like the rise a few months back brought proper attention to the bitcoin and other crypto currencies driving it up the USD exchange rates quite strongly. Demand on the currencies themselves exploded and interest in mining as well. Much to relief of many idealists behind the cryptocurrencies and their miners.
The old school financial markets and governments also woke up and started to fear the rise of the uncontrolled and decentrilized competition. Together they start talking about regulations, controls and banning.
Looks like the cryptocurrencies and their decentralization concept is under attack - and in this round - which may or may not be the final - they are not winning.