Bitcoin hit a low of $6,915.55 late Thursday afternoon, its lowest since Feb. 6, according to CoinDesk's bitcoin price index. That marked a decline of nearly 29 percent for the week and 50 percent for the year so far. Bitcoin had recovered above $7,000 as of 6 p.m. ET.

The largest digital currency by market capitalization fell more than 9 percent to below $7,200, according to CoinDesk's bitcoin price index. That brought the quarter-to-date decline to 48 percent.

Ethereum, the second-largest cryptocurrency by market cap, declined 11 percent to near $397, its lowest since Nov. 23, according to CoinMarketCap. At that price, ethereum was down roughly 29 percent for the week and nearly 47.5 percent for the quarter.

Bitcoin three-month performance

Source: CoinDesk

Some analysts have expected selling in bitcoin and other cryptocurrencies to pick up toward the mid-April deadline to file U.S. taxes as first-time investors realize they need cash to pay capital gains tax.