Bitcoin Most "Crowded" Investment in World

More conservative money managers are worried about bitcoin than ever before.

The soaring digital currency topped the list of "most crowded trades" — a measure of sentiment on which a popular investment could quickly reverse its gains — in Bank of America Merrill Lynch's December global fund manager survey released Tuesday.

The survey found that 32% of respondents named bitcoin as the most crowded trade in the financial world, up from 26% in September when the digital currency first led the list. At the time, bitcoin had surged about 375% for the year to $4,600.

But clearly that was not the top, despite a rocky September for bitcoin in which the digital currency briefly plunged more than $2,000 as China cracked down on cryptocurrencies and J.P. Morgan Chase CEO Jamie Dimon called bitcoin a "fraud" that "won't end well."

Bitcoin has roughly quadrupled since September to briefly trade above $19,000 U.S. in the last week. Fueling part of the rally was the launch of bitcoin futures on the CME, the world's largest futures exchange, and its competitor the Cboe's Futures Exchange.

The BofAML survey, conducted from Dec. 8 to 14, covered 172 global fund managers with a total of $480 billion in assets under management. It's widely considered one of the best surveys of investors conducted on Wall Street.

Another crowded trade is betting on the stocks of U.S. and Chinese technology giants, 29% of respondents said.