They may have lost the battle for Facebook Inc. (FB), but the Winklevoss twins have made a success of their bitcoin venture. The spectacular run-up in bitcoin’s price has made them the digital currency’s first publicly-known billionaires.

Cameron and Tyler Winklevoss used $11 million from their $65 million payout from their Facebook lawsuit against Mark Zuckerberg to invest in bitcoin back in 2013. At that time, the cryptocurrency was priced around $120 and the Winklevoss twins claimed to own almost 1% of all bitcoin in circulation. The price of a single bitcoin is above $11,000 now and the cryptocurrency’s market capitalization is $187.6 billion, as of this writing. Hence, the total value of bitcoins held by the twins is worth more than one billion dollars.    

In an interview with the Financial Times last year, the Winklevoss twins said they “see bitcoin as potentially the greatest social network because it is designed to transfer value over the Internet.” They claim bitcoin is better than gold and “matches or beats” the precious metal across its nine foundational traits, such as scarcity and portability. (See also: Winklevoss Interview: Bitcoin Payment System Worth $400 Billion.) 

The twins have mostly focused on building an ecosystem for bitcoins that will attract institutional investors and day traders to the cryptocurrency. They started Gemini, the world’s first regulated and licensed digital currency exchange. The exchange is regulated as a trust by the New York State Department of Financial Services (NYFDS).

Gemini was among several cryptocurrency exchanges that suffered outages during last week’s bitcoin trading frenzy. However, the twins' application to start a Winklevoss Bitcoin Trust, an ETF, on the Bats exchange was denied by the Securities Exchange Commission (SEC) in March 2017. But the government agency announced last week that it was reviewing that decision. (See also: SEC Denies Winklevoss Twins ETF Application.)  

To be sure, the Winklevoss twins are not the only ones to have profited from bitcoin’s rise. The still-unknown Satoshi Nakamoto, bitcoin’s inventor, is reportedly the holder of 980,000 coins, which is worth approximately $11 billion based on current price levels of over $11,000 per coin. Other prominent investors of bitcoin diluted their investments in the cryptocurrency through sale or by moving it to other currencies, such as Bitcoin Cash. The Winklevoss twins claim to have not sold a single bitcoin since their 2013 purchase. (See also: Who Are The Top 5 Bitcoin Millionaires?)

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