Ethereum co-founder and ConsenSys CEO Joseph Lubin has recently revealed he questions whether Tether’s USDT has been used to manipulate bitcoin’s price last year, when it reached an all-time high near $20,000.

Speaking on Yahoo Finance’s Final Round, Lubin stated he sees Tether as an interesting project, but isn’t completely certain the stablecoin, supposedly pegged to the US dollar 1:1, has been used to manipulate the market.

He said:

Based on our analysis, which involves just talking to a bunch of people in the space, we do believe that tethers are backed 1 to 1 by U.S. dollars in bank accounts… With respect to market manipulations, I’m not sure that market manipulations are related to Tether directly, if they do exist.

Joseph Lubin

Despite its point of view, the CEO noted investors should be wary of the stablecoin, as he expects “many other price stable tokens” to arise and take its place as the number one stablecoin.

Tether USDT is a controversial subject in the cryptocurrency ecosystem. Various critics believe the cryptocurrency is used to pump the market, drawing parallels between the issuance of new USDT and bitcoin’s price rise. Some claim Tether itself doesn’t have $2.7 billion in the bank to back all USDT in existence, and creates them out of thin air.

Tether claims all of its coins are backed by USD held in bank accounts, although it refuses to identify the banks. As CryptoGlobe covered, a study conducted by University of Texas professor John Griffin has suggested tethers have been used to manipulate bitcoin’s price last year.

In fact, an analysis published by Bloomberg looking into Kraken’s USDT trading data found several suspicious features. Last year, the US Commodity Futures Trading Commission (CFTC) subpoenaed both Tether and Bitfinex, a leading cryptocurrency exchange that has the same CEO Tether has.

Back in May, the US Department of Justice (DOJ), working with the CFTC, launched a criminal probe looking into potential bitcoin price manipulation. The investigation was reportedly looking to target illegal activities in the market, like wash trading and spoofing.

 In an attempt to put an end to manipulation allegations Tether hired former FBI director Louis Freeh to look into its financial situation. Freeh’s firm, Sporkin & Sullivan LLP, found the company had enough USD to back all tethers in circulation, plus a $7 million cushion. It noted, however, it wasn’t an official audit.

Lubin, commenting on the future of the cryptocurrency market after the correction that saw most crypto-assets drop from their all-time highs, revealed he believes “there’ll be a series of irrational exuberant price spikes up, followed by corrections.” Each of these spikes, he said, will bring “a wave of new activity and bring fundamental infrastructure to the ecosystem.”

The CEO of ConsenSys, a firm developing decentralized applications (dApps) built on blockchain technology, has argued “trader types” are behind crypto price swings. While prices go up and down, he implied, developers keep building more “fundamental infrastructure.”