Bitcoin prices tumbled to a fresh 15-month low on Thursday as the digital currency rout continued.

Bitcoin BTCUSD, +1.93% fell to $3,230.00, down 6.1% since Wednesday at 5 p.m. Eastern Time on the Kraken exchange—its lowest level since Sept. 15, 2017.

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What are analysts saying

After plunging through $6,000 on Nov. 14, bitcoin has struggled for any meaningful bounce, falling in four of the past five trading weeks, and according to one analyst, the longer it treads water the more susceptible it becomes to another move lower.

“Bitcoin continues to muddle along in the mid-$3K range. The longer we maintain these levels, the less likely it becomes that prices are oversold and poised for a pop,” wrote Jani Ziedins of CrackedMarket. “The public has largely written cryptocurrencies off as a fad and no new money is coming in. The lack of demand will continue to be a big liability.”

Meanwhile, Tom Lee of Fundstrat Global Advisors said fundamentally the bitcoin selloff does not add up. “Given the steep discounts of BTC to our fair value models, the excessive bearish sentiment about fundamentals does not seem warranted,” he wrote in a research note to clients. Lee said his fair value estimate is between $13,800 and $14,800.

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Altcoins and futures trading

Smaller cryptocurrencies — collectively known as altcoins — are moving lower with bitcoin. Ether, ETHUSD, +5.12% is down 6.9% at $83.70, Litecoin LTCUSD, +3.34% has lost 7.3% to $22.68, XRP, XRPUSD, +0.95% is down 4.3% at 29 cents, and Bitcoin Cash, BCHUSD, +4.03% is trading lower by 7.8% at $89.80.

According to data from CoinMarketCap, the market value of all cryptocurrencies is $105 billion.

Bitcoin futures tracked spot prices lower on Thursday. The Cboe Global Markets December contract US:XBTZ8 ended the day down 5.4% at $3,245, and the CME Group December contract US:BTCZ8 finished the session down 6.1% at $3,215.