Prices for some of the most popular cryptocurrencies dropped sharply Monday. One apparent reason: an adjustment from a popular website on its digital-currency price quotes.

A website called coinmarketcap.com on Monday removed data from some South Korean exchanges from its price quotes for a range of virtual currencies including bitcoin, Ethereum and Ripple’s XRP. The move followed a South Korean government crackdown on cryptocurrencies.

The move by coinmarketcap caused some amount of chaos when prices across the board suddenly plunged. In mid-Monday trading, XRP had fallen 26% over the past 24 hours, Bitcoin Cash was down 18%, and litecoin was down 12%. Of the top 40 cryptocurrencies, 31 were down, including bitcoin and Ethereum.

A representative of the website confirmed the moves in an email to The Wall Street Journal, citing “extreme price discrepancy” among South Korean exchanges. The company added in a tweet Monday afternoon that it “excluded some Korean exchanges in price calculations due to the extreme divergence in prices from the rest of the world and limited arbitrage opportunity.”

Coinmarketcap has become one of the most popular destinations for price quotes as the sector surged last year. According to Amazon’s web-ranking service, coinmarketcap is currently the 154th most popular website in the world, in the same ballpark as Chinese retail giant Alibaba.com .