Bitcoin plunged below $13,000 on Friday after losing around a third of its value in just five days, with the digital currency on track for its worst week since 2013 after a blistering ascent to a peak close to $20,000 on Sunday.

The biggest and best-known cryptocurrency had seen a staggering twentyfold increase since the start of the year, climbing from less than $1,000 to as high as $19,666 on the Luxembourg-based Bitstamp exchange on Sunday and to over $20,000 on other exchang ..

“With the end of the year in sight a lot of investors will be taking profits and saying thank you very much and closing their books for the holiday period,” he added.

Bitcoin has had a difficult week. As warnings about the risks of investing in the volatile and unregulated market have continued to sound louder – with Denmark’s central bank governor calling it a “deadly” gamble – there have been more worries over the exchanges on which cryptocurrencies are bought and sold.

CRYPTO-RIVALS

As rival cryptocurrencies slid along with bitcoin, the total estimated value of the crypto market fell to as low as $480 billion, according to industry website Coinmarketcap, having neared $650 billion just a day earlier.

But other cryptocurrencies had surged earlier in the week, with many market-watchers saying investors who felt bitcoin’s price had become stretched were moving into other digital coins, rather than cashing out entirely.

Ethereum, the second-biggest cryptocurrency by market size, soared to almost $900 earlier in the week, up from around $500 just a week earlier. Ripple, the third-biggest, has more than quadrupled in price since Monday.

“A lot of the capital is flowing from bitcoin into alternative coins,” said Shane Chanel, equities and derivatives adviser at ASR Wealth Advisers in Sydney.

Stephen Innes, head of trading in Asia-Pacific for retail FX broker Oanda in Singapore, said that there have also been moves out of bitcoin into Bitcoin Cash, a clone of the original cryptocurrency. Oanda does not handle trading in bitcoin.