Bitcoin plunged at the end of a rocky week, taking the digital currency below $12,000 and down more than 40 percent from its record high hit Sunday.

Bitcoin had rallied to a record high above $19,800 on Sunday and was trading near $15,500 for much of Thursday New York time, according to Coinbase. But an afternoon selloff accelerated into the night, and bitcoin dropped more than 30 percent Friday morning to $10,770 on the exchange.

With the decline, bitcoin has now fallen 40 percent in just five days and lost about $7,000.

Bitcoin futures also tumbled Friday. The CME bitcoin futures expiring in January, which launched Sunday, fell nearly 20 percent to $12,265 in morning trading. The Cboe bitcoin futures contract, which launched on Dec. 10, fell 23 percent to $11,750.

CME sent a notice saying the futures market was open and at limit. A futures trader confirmed to CNBC that trading appeared to be halted.

Coinbase is the leading U.S. platform for buying and selling major digital currencies, and also operates an exchange for institutional investors called GDAX. On Tuesday, Coinbase surprised many by announcing it was launching trading in the bitcoin offshoot, bitcoin cash. The company had said for months it would allow withdrawals of bitcoin cash on Jan. 1, 2018, and notify customers of other changes beforehand.

In the last several days, many Reddit and Twitter users have also complained they are unable to complete transactions smoothly on Coinbase. The company said on its status website that since last Friday, high transaction volumes were delaying wire transfers. A Wednesday update said “wire deposits and withdrawals may be delayed by up to 5 business days.”

(AP)