Like many crypto-rich entrepreneurs, Tristan D’Agosta shirks the limelight. The sometime music composer's cryptoasset exchange Poloniex soared after it became one of the first to list Ethereum in 2016. In February, Fortune broke the news that fintech startup Circle bought his exchange in a deal valued at $400 million. Circle has been cleaning up Poloniex’s backlog of customer service inquiries ever since.
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