Tether study challenged the market integrity of bitcoin’s 2017 boom

On June 13, 2018, University of Texas researchers John Griffin and Amin Shams released a working paper arguing that concentrated flows of tether, the dollar-linked digital token then commonly identified as USDT, were most consistent with deliberate support of bitcoin and other cryptocurrency prices during the preceding boom.

The paper did not establish through account records, testimony or a regulatory finding that manipulation occurred. It presented an empirical hypothesis built from public blockchain transactions, exchange-related wallet labels and market-price data. That distinction was central on June 13, 2018: the research raised a serious market-integrity question, but its statistical conclusions were not a legal judgment or direct proof of who controlled individual transactions.

What the researchers measured

Griffin and Shams examined bitcoin and Tether blockchain activity principally from March 1, 2017 through March 31, 2018. Their sources included CoinAPI intraday prices, CoinMarketCap daily data, CoinDesk hourly bitcoin prices and public Bitcoin and Omni Layer transaction records. They used wallet-clustering methods and public information to associate groups of addresses with exchanges, including Bitfinex, Poloniex and Bittrex.

The authors tested two broad explanations. Under their demand-driven hypothesis, new tether entered circulation in response to investors supplying dollars and seeking a transferable dollar substitute. Under their supply-driven hypothesis, tether could be issued and deployed to buy cryptocurrencies irrespective of corresponding cash demand, particularly after market declines.

Their event study isolated 87 hours from a total of 9,504. Each selected hour followed tether issuance within the preceding three days, a negative bitcoin return in the preceding hour and specified two-way flows exceeding 200 bitcoin-denominated units on the Tether and Bitcoin blockchains. Those 87 hours represented 0.92% of the measured series.

A large association, not a settled causal result

The paper calculated that bitcoin rose from approximately $1,190 to approximately $7,000 over its March 1, 2017–March 31, 2018 window, a 488% buy-and-hold return under the authors’ price series. When the return immediately following each of the 87 selected flow events was set to zero, their synthetic series ended near $4,100, or a 245% rise. From that counterfactual calculation, the researchers concluded that the selected hours were associated with approximately 50% of bitcoin’s buy-and-hold return over the window.

“Associated” is the necessary word. Removing observed returns from a constructed series does not demonstrate that the returns would have been zero without the tether flows. The procedure also selected events using prior issuance, negative returns and large blockchain flows, so interpretation depends on the wallet labels, timing rules and assumed relationship between transfers and exchange trading.

The researchers additionally reported that tether-related buying clustered below bitcoin price levels in $500 increments and that the strongest flows followed market downturns. They interpreted those patterns as more consistent with price support than with ordinary investor demand.

Why the paper mattered on June 13

Tether served as dollar-like trading infrastructure for exchanges that could not reliably maintain conventional banking access. Questions about its issuance therefore reached beyond one token: confidence in USDT affected trading pairs, exchange liquidity and the interpretation of cryptocurrency prices formed on tether-denominated venues.

Bitfinex chief executive JL van der Velde rejected the paper’s interpretation in a statement reported on June 13, 2018, saying Bitfinex and Tether had not engaged in market or price manipulation. Same-day coverage also noted that neither company had been accused of wrongdoing in connection with the study’s claims.

The responsible event-date conclusion was consequently narrow. Griffin and Shams had documented an unusual and economically large statistical pattern. They had not independently inspected complete bank records, identified the beneficial owner behind every clustered wallet or obtained private order-level records proving intent. The publication nevertheless shifted the debate from general suspicion toward a testable account of how stablecoin issuance and exchange flows might influence crypto prices.