Bitcoin fell from $37,156 at 6.30am BST to $35,453 at 11.00am BST. This was a fall of five percent in just a few hours.
Separately the value of Ethereum declined from $2,565 at 6.15am BST to $2,439 at 11am BST.
Bitcoin has had an unstable 2021 with its value fluctuating between $30,000 and $65,000.
It followed a year of huge growth in the virtual currency’s value in 2020.
Earlier this month the value of Bitcoin, Ethereum and Dogecoin fell sharply following new regulations in China.