Bitcoin prices rallied Sunday, topping the $20,000 level again after falling to an 18-month low Saturday amid a weeks-long cryptocurrency rout.

Bitcoin BTCUSD, +0.48% surged about 16% in the past 24 hours, as of 5 p.m. Sunday, to $20,598, making up for much of its Saturday losses, when it slid as low as $17,630, according to Coinbase data.

Ethereum ETHUSD, -0.97% prices surged as well Sunday, jumping 26% to $1,137 as of 5 p.m. Sunday.

Cryptocurrencies trade 24 hours a day, and often fluctuate wildly on weekends, when financial markets are closed. A number of crypto bulls have called the recent plunge in crypto values a prime buying opportunity, while critics warn the fundamentals have not changed and it could slump further.

Read: Bitcoin skids under $20,000 in Minsky Moment for crypto: ‘Psychologically for a lot of people, this is galling’

Vinny Langham, chief executive of livestreaming platform Waitroom, tweeted Sunday: “This could signify the bottom, if it retakes/holds $20k quickly by Tue/Wed. Otherwise, we’re in a bear market for a while and $20k becomes major resistance.”

The recent crypto selloff started with the collapse of the Terra blockchain in May, and has has coincided with the Federal Reserve hiking interest rates amid recession worries.

Bitcoin has lost about 55% of its value year to date, according to Coinbase data, and is off about 70% from its all-time high near $69,000 in November. Ethereum, meanwhile, is down 69% in 2022.