Researchers studying 2017’s dramatic bitcoin bull run have found that nearly the entire rise of the digital currency can be attributed to “one large player” – or “whale.”

Finance professors John Griffin and Amin Shams – instructors at University of Texas and the Ohio State University, respectively – analyzed over 200 gigabytes of data for the transaction history between bitcoin and tether, another digital currency. Tether is an asset known as a “stablecoin,” which has its trading value connected to the dollar, CNBC reported..

The professors’ study found that tethers being traded for bitcoins revealed a pattern.

“We find that the identified patterns are not present on other flows, and almost the entire price impact can be attributed to this one large player,” Griffin and Shams wrote. “We map this data across both blockchains and find that the one player or entity (labeled as 1LSg throughout the paper) is behind the majority of the patterns we document.”

Griffin and Shams were able to follow the clusters of data to a source: “One large account at Bitfinex.” The digital currency exchange Bitfinex is one of the largest in the world. The study found that, through Bitfinex, the single player was able to manipulate demand for bitcoin via “extreme” flows of tethers.

The manipulation occurred as bitcoin rose to an all-time high of nearly $20,000 in late 2017, the study found.

“One of the SEC’s top worries is that crypto is subject to manipulation. This study appears to lend credibility to that argument,” Cowen analyst Jaret Seiberg said in a note on Monday.

The study comes after an analysis published in March found that 95% of bitcoin spot trading is faked. The survey, created by cryptocurrency asset manager Bitwise for the SEC, found that only $273 million of about $6 billion in average daily bitcoin volume was legitimate.

Cowen said Griffin and Shams’ study will likely add even more scrutiny of bitcoin and cryptocurrency at large, especially from regulators and lawmakers.

“We see this as further souring Washington on crypto and believe it is negative for efforts to launch crypto ETFs and for Facebook to launch Libra,” Seiberg added.

Libra is Facebook’s cryptocurrency project, which has seen several major backers drop out in the past month.

While the latest study doesn’t identify the manipulator, the professors suggest those running Bitfinex either knew of the operation or were even possibly assisting the scheme. Bitfinex’s general counsel Stuart Hoegner told the Wall Street Journal that the study “lacks academic rigor,” saying that “it is the global rise of digital currency that has driven the market’s demand for tether.”

Both Bitfinex and Tether Ltd, the company that controls tether, are owned and operated by the same people. Both companies are being investigated for alleged fraud by the US Department of Justice and the New York Attorney General.

In 2019, there have been much rarer occasions of bitcoin price rallies. Still, the pattern of sharp and immediate price climbs, seemingly out of nowhere, support the observation that lifting the price of bitcoin may be a concerted effort, Cryptovest reported.

Bitcoin traded around $9,400 early Tuesday.