BlackRock won’t be launching an ETF for bitcoin any time soon — at least not until cryptocurrencies become “legitimate.”

The world’s largest asset manager is not launching an exchange traded fund for cryptocurrency — at least not until the industry grows up a bit.

“I wouldn’t say never, when it’s legitimate, yes,” BlackRock CEO Larry Fink said at the New York Times Dealbook Conference in Manhattan Thursday.

The Securities and Exchange Comission has shared its own doubts about a bitcoin ETF, and has yet to approve any of the multiple applications. The agency published a letter in January pointing to “significant investor protection issues that need to be examined” before sponsors can offer these funds to retail investors.

Bitcoin was founded in 2008 to bypass banks and other government institutions. But for now, Fink said that level of independence could be a major roadblock for cryptocurrencies.

“It will ultimately have to be backed by a government,” said the CEO of BlackRock, which oversees approximately $6.4 trillion of assets. “I don’t sense that any government will allow that unless they have a sense of where that money’s going for tax evasion and all of these other issues.”

Fink pointed to another risk factor — bitcoin’s anonymity. The digital currency has been used in dark web marketplace to facilitate transactions for guns, drugs and other illicit goods. It has been categorized as the currency of choice for criminals by those who doubt bitcoin’s place in modern finance.

“I do see one day where we could have electronic trading for a currency that could be a store of wealth,” Fink said. “But right now the world doesn’t need a store of wealth unless you need that store of wealth for things you should not be doing.”

Blockchain is another story

Fink joined a choir of Wall Street CEOs — including J.P. Morgans’s Jamie Dimon — who have expressed doubts about cryptocurrencies but applaud their underlying technology. J.P. Morgan Chase, IBM, Deloitte, Amazon and Facebook are among those working on private blockchain solutions for businesses, which for the most part have nothing to do with cryptocurrencies.

“We are a huge believer in blockchain,” Fink said. “The biggest use for blockchain will be in mortgages, mortgage applications, mortgage ownership, anything that’s labored with paper.”

Former White House Economic Advisor and former Goldman Sachs President Gary Cohn joined the board of a blockchain start-up in October. Other Wall Street veterans, including former head of J. P. Morgan’s global commodities business, Blythe Masters, have left traditional finance to run blockchain companies.

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