If you’ve heard about the massive gains being enjoyed by bitcoin recently, then googled the digital currency to see what all the fuss is about, some of the cryptocurrency’s investors may want to thank you.

Bitcoin prices show a notably high correlation with Google search trends for the word “bitcoin,” according to Chris Burniske, a bitcoin expert who was previously a blockchain analyst at ARK Invest.

In a series of recent tweets, Burniske speculated that an increasing price drives the kind of interest in bitcoin that sends people looking for information about it online, and “that interest further drives the price of $BTC,” something he joked was “a virtuous Satoshi cycle,” in reference to Satoshi Nakamoto, the pseudonym used by the mysterious creator, or creators, of bitcoin.

Such a correlation seems to be unique to bitcoin, which is increasingly followed by investors but remains a small and thinly traded asset relative to stocks or bonds. Because of their vastly larger size and greater levels of liquidity, Google searches for stocks—as measured by the Dow Jones Industrial DJIA, -0.87% , a favorite proxy for retail investors—don’t track equity prices, let alone lead them.

The price of a single bitcoin BTCUSD, +0.93% traded down 0.9% to $4,166.22 on Wednesday, having recently hit a record high of $4,483.55. Still, a current levels, it has more than quadrupled thus far this year, a move that has lifted its total size to nearly $70 billion, making it comparable to Dow component Caterpillar Inc. CAT, -0.96% , according to data from CoinMarketCap.

See a chart of the biggest digital currencies in the world

Bitcoin’s rally has been among the strongest gains seen of any asset in 2017, although Ether—bitcoin’s chief rival, which runs on the Ethereum network—has soared more than 3,800%.

According to Google trends, the search term “bitcoin” is reaching peak popularity in August 2017, while searches for “ethereum” have tapered off. (Bitcoin is in blue in the following chart.)

The growth in bitcoin this year has come alongside growing interest in overall cryptocurrencies, as well as increased regulatory interest and public debates over how it can manage at its current size. Recently, a new digital currency—called Bitcoin Cash—erupted out of the original version to more rapidly process transactions in larger units, an issue related to bitcoin “scability.”

What is the future of bitcoin?

The gains have been so large that major Wall Street banks have started to weigh in on the nascent sector. Both Wells Fargo and Goldman Sachs recently published primers on bitcoin for their clients, while one Morgan Stanley analyst called it a poster child for speculation. The investment bank had previously said that in order for bitcoin to rise further—it had been trading around $2,750 at the time—government regulation would be necessary.

See also:Bitcoin is up over 400% in the past year—what’s stopping it from going mainstream?

Bitcoin’s evident connection to internet search interest—when combined with its continuing move into the mainstream—may suggest that prices have nearly unlimited upside potential, something some proponents more or less agree with. John McAfee, the founder of his namesake antivirus software company, as well as a former fugitive and passionate cryptocurrency backer, recently tweeted that he would “eat [his] d--k on national television” if bitcoin didn’t hit $500,000 within three years.

Burniske disputed that general idea, noting that three peaks in Google search trends were accompanied by “three of bitcoin’s six price bubbles.”

“The virtuous Satoshi cycle can overheat though, as Google search activity divorces from its tight tango with bitcoin’s price,” he tweeted earlier this week.

Burniske defines bitcoin bubbles as the price doubling or more in a 30-day period. That is currently the case, as it was below $2,000 per bitcoin on July 16. “After every bubble there’s a crash,” he tweeted, with some drops exceeding 90%. However, he added that “those were *very* different bitcoin markets” [emphasis in original] as they had “thin liquidity, fragile exchanges, and a fraction of the users and investors,” something he suggested could limit downside in the event of another sharp downtrend.

Read this from June: Is bitcoin in a bubble? This metric suggests there’s more room to grow