Bitcoin's struggles are continuing into 2019.

The world's largest cryptocurrency dropped 9 percent on Thursday morning to a low of $3,570.29, according to industry data site CoinDesk. The sudden and sharp drop brings bitcoin's one-year losses to more than 70 percent.

Other major cryptocurrencies struggled, too. Ether fell 15 percent while XRP dropped 9 percent, according to CoinDesk.

Analysts did not point to any particular catalyst for Thursday's cryptocurrency dip. Mati Greenspan, senior market analyst at eToro, said clients had been asking — but there doesn't seem to be any real reason for this drop, "neither technical nor fundamental."

"The one interesting thing about this movement is that it seems to be an exact reversal of the surge that happened on Sunday afternoon," Greenspan said. "At this point, the gains made since the start of the year have now been reversed and we're back to a neutral 2019."

Bitcoin and other cryptocurrencies have failed to recover to their peaks reached around this time last year. The retail mania has certainly worn off as the entire market capitalization has dropped 85 percent in a year, according to Coinmarketcap.com.

Investors had been awaiting more institutional adoption this year, and the launch of a series of bitcoin futures. Both the Intercontinental Exchange, or ICE (parent company of the New York Stock Exchange) and the Nasdaq plan to launch bitcoin futures this year, despite the ongoing bear market.

So far, the Commodity Futures Trading Commission, which regulates bitcoin, has approved two crypto futures products — one from the Chicago Board Options Exchange and another by the Chicago Mercantile Exchange. Still, SEC Chairman Jay Clayton said in November that he needs to see better custody solutions surveillance before he would feel "comfortable" allowing a crypto exchange traded fund, or ETF, to come to market.

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