Some people think bitcoin’s spectacular price rise last year was manipulated by a cryptotoken called Tether that’s supposed to be pegged to the US dollar. Now, an anonymous report answers the question: What would bitcoin be worth without Tether? The answer: around $4,500, based on the current bitcoin price of about $7,600.

Tether is a crypto token, or coin, that’s supposed to be pegged to the dollar and backed by real dollar reserves in a bank account somewhere. Tether’s coins are often used for dollars on cryptocurrency exchanges because of the reserve claim. Traders use Tether’s coins to cash in and out of bitcoin quickly, avoiding the lengthy process of converting the sums in and out of fiat currency. However, Tether hasn’t provided audits to prove its reserves exist.

The uncertainty surrounding Tether has made crypto investors uneasy, an unease that became alarm when Bloomberg reported that Tether was subpoenaed by the US commodities trading regulator in December. Bitcoin’s price has fallen about 25% since that news broke.

A group of investors called the 1000X Group, who look for the next big crypto hit, recently commissioned a report to determine Tether’s influence on the bitcoin price. Based on publicly available information, the report found that bitcoin’s price rose about 40% in the two-hour windows after each batch of newly issued Tether coins arrived at the exchange Bitfinex’s digital wallet, between last April and this January. The author claims anonymity because of fear of “backlash” from expressing an “unpopular opinion.”

Crypto market investors think the report’s analysis is credible. “It’s a great report—awesome data analysis,” says Alex Sunnarborg, who runs a crypto hedge fund called Tetras Capital. ” I think it shows that a huge piece of bitcoin’s price movement has directly followed Tether issuances very well.”

The price of bitcoin stood at $15,000 at the end of the period analyzed by the report, which is Jan. 4. If 40% of that price was directly attributed to Tether issuance, then the price of bitcoin without those new Tethers would have been about $9,000.

The price of bitcoin at press-time is just over $7,600; applying the 40% Tether discount gives us a price of $4,500. But analysts caution that some of the news around Tether, including the subpoena from US regulators, could already be accounted for in the current bitcoin price, meaning the discount shouldn’t be as deep.

The report’s author paints an even more bearish outlook in some scenarios. If the bitcoin price was propped up by Tethers that were just magically created each time the price fell, as the author’s analysis suggests, then the subsequent rallies potentially wouldn’t have been as powerful over the last year. All told, the author believes the price of bitcoin could be just 30% of the price quoted on exchanges during the study period. That means instead of $15,000 in early January, the price of bitcoin should have been $4,500.

There’s one more analysis that suggests the bitcoin price should be even lower. The author extrapolates a linear trend-line for the price starting last April, when Tethers began to be issued in earnest. That trend-line puts the price of bitcoin at just $2,000 instead of $15,000.

“It is highly unlikely that Tether is growing through any organic business process, rather that they are printing in response to market conditions,” the author writes in summary.

The author’s recommendation? An audit showing that every Tether token is backed by a dollar. There’s just one problem: The auditor Tether hired for this purpose, a New Jersey firm called Friedman LLP, is no longer working with the crypto issuer. Quartz contacted Friedman for clarification but did not receive a response. Tether said last week (Jan. 27) that the relationship was “dissolved” when questioned by the industry news source CoinDesk.

While the mystery around Tether deepens, a prolonged bear market might be a chance to clear things up.