Bitcoin soared to its highest in almost five months on Tuesday, pulling smaller cryptocurrencies up with it, after a major order by an anonymous buyer set off a frenzy of computer-driven trading, analysts said.

The original cryptocurrency soared as much as 20 percent in Asian trading, breaking $5,000 for the first time since mid-November. By mid-afternoon, it had settled around $4,800, still up 16 percent in its biggest one-day gain since April last year.

Bitcoin surged to near $20,000 in late 2017, the peak of a bubble driven by retail investors. But last year prices collapsed by three-quarters, with trading dominated by smaller hedge funds and crypto-related firms.

Today’s gain was probably triggered by an order worth about $100 million spread across U.S.-based exchanges Coinbase and Kraken and Luxembourg’s Bitstamp, said Oliver von Landsberg-Sadie, chief executive of cryptocurrency firm BCB Group.

“There has been a single order that has been algorithmically-managed across these three venues, of around 20,000 BTC,” he said.

“If you look at the volumes on each of those three exchanges – there were in-concert, synchronized, units of volume of around 7,000 BTC in an hour.”

Still, analysts could not point to any specific developments that could explain the mystery buyer’s big order.

Cryptocurrency markets had until today seen a period of relative calm through the year, with bitcoin trading around $3,300 and $4,200.

Big institutional investors have largely stayed on the sidelines. Concern over security breaches and regulatory uncertainty were cited as reasons for the lack of mainstream enthusiasm in digital coins.

In a sign of bitcoin’s failure to gain an equal footing with conventional markets, Cboe Global Markets - which offered the first U.S. bitcoin futures contracts in 2017 - said last month it would no longer offer bitcoin futures contracts.

CME Group Inc continues to list its futures product, which launched soon after Cboe.

“ALTCOINS” ALSO SURGE

Outsized price moves of the kind rarely seen in conventional markets are common in cryptocurrency markets, where liquidity is thin and prices opaque. Big orders tend to spark buying by algorithmic traders, said Charlie Hayter, founder of industry website CryptoCompare.

As bitcoin surged, 6 million trades occurred in an hour, Hayter said - three to four times the usual amount, with orders concentrated on Asian-based exchanges.

Bitcoin’s surge sent smaller cryptocurrencies, known as “altcoins,” trading higher. Ethereum’s ether and Ripple’s XRP, respectively the second- and third-largest coins, both jumped by more than 10 percent.

Price moves of smaller coins tend to be correlated to bitcoin, which still accounts for just over half of the value of the cryptocurrency market.

“Usually bitcoin is the leader of the market and altcoins tend to follow, as far as direction and sentiment is concerned,” said Mati Greenspan, an analyst at eToro in Israel. “Today bitcoin is in the driving seat.”