OpenSea

OpenSea is a marketplace for buying and selling non-fungible tokens (NFTs) that in 2025 expanded into trading of crypto tokens across multiple blockchains through a rebuilt platform called OS2. Devin Finzer and Alex Atallah founded the company in December 2017, when CryptoKitties was the main NFT use case on Ethereum. Finzer is chief executive, and Wikipedia lists the headquarters as Miami. Atallah left the company in 2022.

OpenSea went through Y Combinator and raised about $2 million early on; TechCrunch describes a $2 million 2017 round from Founders Fund and several crypto-focused firms, while Wikipedia records a $2.1 million pre-seed. In March 2021 Andreessen Horowitz led a $23 million Series A, with angels including Naval Ravikant, Mark Cuban, Alexis Ohanian, Dylan Field and Linda Xie. Andreessen Horowitz led again in July 2021, a $100 million Series B at a $1.5 billion valuation with Coatue, CAA, NEA's Connect Ventures and angels including Michael Ovitz, Kevin Hartz, Kevin Durant and Ashton Kutcher. In January 2022 Paradigm and Coatue led a $300 million Series C at a $13.3 billion valuation. Across these rounds the company raised roughly $425 million.

The Series C landed near the top of the NFT cycle. TechCrunch reported more than $2.4 billion of transaction volume in the 30 days before the January 2022 announcement and hundreds of millions of dollars of fees in 2021. Volume then fell sharply, and the company cut staff in July 2022. A former product head, Nate Chastain, was convicted of NFT insider trading in 2023, a conviction a federal appeals court overturned in July 2025. The SEC sent OpenSea a Wells notice in August 2024 and closed the investigation in February 2025. OpenSea then relaunched as OS2, bought the wallet app Rally in July 2025, and in October 2025 handled about $1.6 billion of crypto trades against $230 million of NFT transactions.

OpenSea is a case study in valuation timing. The Series A to Series C step-up was roughly 9x in six months, and the Series C investors entered at the peak of a market that contracted soon after. Andreessen Horowitz, which led two rounds at much lower prices, has a far better entry than the 2022 leads. No IPO or sale has occurred, so none of the backers, including early crypto funds, has a priced exit eight years after founding.