Bitcoin, the largest cryptocurrency by market value, fell about 5% to a three-month low of $18,387.

Ether, the second-largest cryptocurrency, fell 3% to a two-month low of $1,285 and is down more than 10% in the past 24 hours. Most other smaller tokens were down.

The Ethereum blockchain, which underlies the ether token, received a major update over the weekend called Merge, which changed the way it processes transactions and reduced energy consumption.

The value of the token fell amid some speculation that remarks by SEC Chairman Gary Gensler last week implied that the new structure could attract additional regulation. Trading around the update was also curtailed.