Ether, the token transacted on the ethereum blockchain, rose 3% on the Bitstamp exchange to $3,144.81 in morning deals in London. It is up 325% for the year so far, easily outpacing a 95% rise in the more popular bitcoin.

(GRAPHIC: Ethereum hits record high, quadruples in value in 2021 - )

In part, the big rally is a catch-up to late 2020 gains in bitcoin, said James Quinn, managing director at Q9 Capital, a Hong Kong cryptocurrency private wealth manager.

It also reflects improvements to the ethereum blockchain, he said, and a growing shift towards "DeFi", or decentralised finance, which refers to transactions outside traditional banking for which the ethereum blockchain is a crucial platform.

"At first, the rally was really led by bitcoin because as a lot of the institutional investors came into the space, that would be their natural first port of call," Quinn said.

"But as the rally has matured over the last six months, you have DeFi and a lot of DeFi is built on ethereum."

The launch of ether exchange-traded funds in Canada and surging demand for ether wallets to transact non-fungible tokens such as digital art have also pushed up the price.

The ether/bitcoin cross rate has soared more than 100% this year and hit a 2.5-year high on Sunday, pointing to a degree of rotation into the second-biggest cryptocurrency as investors diversify their exposure.

"Surging DeFi volumes continue to push ethereum prices higher as investors gain confidence in crypto and see ethereum as a safe second-place asset," said Jehan Chu, managing partner at Hong Kong blockchain venture capital firm Kenetic Capital.

Illustrating the momentum for such new transactions, Bloomberg reported last week that the European Investment Bank plans on issuing a digital bond over the Ethereum blockchain, while JP Morgan plans a managed bitcoin fund.

Venture capital giant Andreessen Horowitz is looking to raise a new fund of as much as $1 billion to invest in cryptocurrencies and crypto start-ups, the Financial Times reported on Friday, underlining interest in the sector.

Bitcoin, the world's biggest crypto asset with more than $1 trillion in market capitalisation, regained the $50,000 mark last week and hovered around $58,700 on Monday, up about 4% but well below its record high at $64,895.22.

The U.S. dollar was broadly steady. [FRX/]

(Reporting by Tom Westbrook and Vidya Ranganathan; Additional reporting by Ritvik Carvalho; Editing by Himani Sarkar, Tommy Wilkes and Mark Heinrich)

By Ritvik Carvalho and Tom Westbrook