Bitcoin, the biggest cryptocurrency by market value, dropped about 5 percent to a three-month low of $18,387.
Ether, the second largest cryptocurrency, fell 3 percent to a two-month low of $1,285 and is down more than 10 percent in the last 24 hours. Most other smaller tokens were deeper in the red.
The Ethereum blockchain, which underpins the ether token, had a major upgrade over the weekend called the Merge that changes the way transactions are processed and cuts energy use.
The token’s value has fallen amid some speculation that remarks last week from U.S. Securities and Exchange Commission Chairman Gary Gensler implied the new structure could attract extra regulation. Trades around the upgrade also were unwound.
“It’s speculation as to what might or might not happen,” said Matthew Dibb, COO of Singapore crypto platform Stack Funds, on the regulatory outlook.
“A lot of the hype has come out of the markets since the Merge,” he said. “It’s really been a sell-the-news type of event,” he added, given the nervous global backdrop, and said ether could test $950 in coming months.
Cryptocurrencies fell to fresh lows on Monday on regulatory concerns and as investors globally turned shy on risky assets with interest rate rises looming around the world, Reuters news report said.