Bitcoin’s volatility needs to ease to prevent the token’s rally from fizzling, according to JPMorgan Chase & Co.

Unless swings recede rapidly, the current price of the largest cryptocurrency “looks unsustainable,” strategists led by Nikolaos Panigirtzoglou wrote in a note Tuesday.

Bitcoin has been barreling through records, scaling another peak above US$51,000 on Wednesday. Tesla Inc.’s recent US$1.5 billion purchase and MicroStrategy Inc.’s plan to expand its holdings of the token by selling US$600 million in convertible bonds added to the buzz around cryptocurrencies. On the flip side, some see a mania likely to end in a bust akin to the implosion in 2017.

JPMorgan said Bitcoin’s market value has risen by about US$700 billion in the past five months despite an aggregate institutional inflow of only around US$11 billion. Limited supply of the token and retail demand may be pushing up prices, Panigirtzoglou wrote.

“Movements since January this year appear to have been more influenced by speculative flows,” the team said.