Bitcoin briefly tumbled below $30,000 on Thursday, as the cryptocurrency continued a slide from record levels.

The digital currency dropped as much as 17% to $29,246.77, wiping out about $100 billion from the market, according to data from CoinDesk. It’s since pared losses slightly Friday, climbing back above $30,000 after trading beneath that level for over an hour.

Bitcoin was last trading down around 3% at a price of $31,668. It’s fallen more than 12% so far this week, and is now down roughly 25% since peaking at $41,940 earlier this month.

The latest plunge, which comes without any clear reason, underscores the volatility of a currency that’s become a popular investment for day traders in recent years even as it still has limited real-world application. Bitcoin rose over 300% in 2020, closing the year just above $29,000.

Ether, the digital currency that’s second to bitcoin in total value, dropped even more on Thursday, declining 22% to $1,053.80. It’s since recouped some of its losses, off 3% at a price of $1,204, but still 16% below its high from earlier this week, according to CoinDesk. Ether rose 471% last year.

President Joe Biden picked Gary Gensler, the former chairman of the Commodity Futures Trading Commission and an ex-Goldman Sachs banker, to be the next chair of the Securities and Exchange Commission. Gensler taught about cryptocurrencies at the Massachusetts Institute of Technology, starting in 2018.

However, Biden’s choice of Treasury Secretary, former Federal Reserve Chair Janet Yellen, is a crypto skeptic who warned earlier this week that the government may need to “curtail” the use of virtual currencies to prevent illicit activity.