Ether increased as much as 6.9% to $3,145, gaining for a fourth day amid the Ethereum network’s London upgrade, which reduces the pace of growth in the coins. Bitcoin and Ether reached their highest levels in more than two months after a major Ethereum upgrade and despite uncertainty over crypto rules in the U.S. infrastructure plan.

Bitcoin gained as much as 4.1% to $44,463 on Saturday, its highest level since May 18. Ether increased as much as 6.9% to $3,145, gaining for a fourth day amid the Ethereum network’s London upgrade, which reduces the pace of growth in the coins

“A mood of optimism appears to have returned to cryptocurrency markets,” Paolo Ardoino, chief technology officer at Bitfinex, said in comments Friday. “Bitcoin is leading the charge while Ethereum continues to make gains” after its network upgrade. Still, he said, “the turbulence that we’ve seen in crypto markets over recent weeks is unlikely to subside.”

Cryptocurrencies are showing signs of life again after pulling back significantly from record highs in recent months, a setback blamed on concerns about China’s crackdown and Elon Musk-fueled questions about Bitcoin’s energy usage.

Bitcoin, however, is approaching its 50-day moving average, a mark it hasn’t touched since May 26. And Ether is over $3,000 again, after its first run above that level lasted for just a couple of weeks.

One factor still creating uncertainty: The U.S. infrastructure bill currently making its way through Congress, which has dueling amendments that address reporting requirements for crypto transactions and tax collection. The bipartisan group that drew up the legislation was counting on the extra tax revenue generated to help pay for some of the bill’s costs.

Still, that isn’t stopping momentum in crypto, the market value of which has risen by about 10% in the past 24 hours to $1.89 trillion, according to CoinGecko.com. Other tokens like Binance Coin, Cardano, XRP and Dogecoin are also rallying.