Listen to Tech Tent: When crypto met football on BBC Sounds.
Socios told BBC News it had sold $270m-300m worth of coins through its app. It would not say how much money goes directly to clubs.
Buyers must first convert their money into the company's own crypto-currency, Chiliz.
The research, by crypto-analysts Protos, suggests many buyers are speculatively trading their tokens like other crypto-currencies in an attempt to make money.
But the value of many fan tokens had decreased since they were initially sold by the clubs.
BBC News asked every Premier League team and some major European sides about their plans for, and views on, the new trend.
Only one was happy to comment.
A Brighton and Hove Albion spokesman said: "We have not sold these products and have no plans to enter these markets."
Since crypto-currency products are based on a public ledger, known as the blockchain, Protos was able to determine:
Lazio, Manchester City, Porto, and Santos appeared to generate the most sales
the fan tokens to have generated the most revenue were Lazio's - up to $130m
Manchester City and Lazio tokens had dropped the most in value - down 50% and 70% since the end of the first day of trading
the tokens of two clubs, Inter Milan and Turkish side Trabzonspor, had increased in value more than Bitcoin over the past year
"Fan tokens are being traded more actively than you'd expect for this type of fan-engagement product," Protos director of news David Canellis said.
"Generally, small crypto-currencies like these fan tokens can be incredibly volatile due to the small amount of people who want to trade them.
"Speculators know this, so I would consider much of the trade in fan-token markets to be powered purely by speculators seeking short-term profits."
Socios disputed the claim that many of its users were speculators, saying that the "vast majority" held tokens to engage with their clubs, with "most holding just a few tokens".