The total value of cryptocurrencies held by Ethereum co-founder Vitalik Buterin has increased by $19 million over the past week amid a broader resurgence in the digital asset markets.

Data provided by blockchain analytics firm Arkham Intelligence shows that the balance of Buterin’s known crypto wallets rose from $561 million on Dec. 26 to $580 million on Jan. 2 — an increase of nearly 3.4%. The gains coincide with a spike in the price of Ethereum (ETH) and other major cryptocurrencies like Bitcoin (BTC).

Buterin’s holdings are dominated by Ethereum, which explains the gain. Ethereum climbed from around $2,218 to nearly $2,370 over the same period, increasing around 6.6%.

Ethereum is the only part of this $580 million portfolio worth millions, followed by $635,000 of Kyber Network (KNC) and $456,000 of Wrapped Ethereum (WETH). The development follows Buterin’s recent criticism for proposing cutting Ethereum’s security to increase the network’s efficiency.

Vitalik Buterin is a Russian-Canadian computer programmer best known as Ethereum’s co-founder. He was born in 1994 in Kolomna, Russia, and moved with his family to Canada when he was six. As a child, Buterin displayed an aptitude for math, programming, and economics. He first became interested in cryptocurrency and blockchain technology as a teenager.

Buterin co-founded Bitcoin Magazine, one of the first serious publications dedicated to cryptocurrencies, and in 2013, Buterin published the white paper for Ethereum. He argued Bitcoin needed a scripting language for application development. Ethereum launched in 2015 after starting development in 2014 with Buterin as a co-founder.