The "only bubble" respondents of an Investopedia survey said they were concerned about one involving bitcoin, according to the U.S. financial website's editor-in-chief.

Appearing on the business segment of Fox News on Wednesday, Caleb Silver said that while as many as 20% of the respondents had added bitcoin to their portfolios over the past year, it didn't stop many from fearing a potential bubble pop.

Of those surveyed, 62% believe bitcoin is in bubble territory.

"They are not fearing a bubble in equities, they are not fearing a bubble in SPACs as much as they are fearing one in bitcoin and other cryptocurrencies," said Silver.

Special purpose acquisition companies (SPACs) are listed firms with no operational capacity that are sought by companies – such as eToro this week – seeking to go public and raise capital through so-called back-door listings.

See also: Blockchain Mortgage Platform Figure Launches SPAC to Raise $250M

Silver said respondents' concerns were founded on "good reason" because the cryptocurrency market is up substantially higher despite no specific catalyst outside of increased institutional investment.

Bitcoin broke new ground on March 13, rising to an all-time high of around $61,556. The world's largest cryptocurrency by market cap is changing hands for around $58,340 at press time, up 100% year to date.