Castle Island Ventures is a venture capital firm focused exclusively on public blockchains, backing entrepreneurs who build infrastructure and application companies on those protocols. Castle Island Ventures's Twitter Score is 78 out of 1000 (a Good rating) as of August 2026, ranking #10,167 (top 5%) among 484,166 tracked accounts.
Castle Island Ventures was co-founded by Matthew Walsh and Nic Carter, both formerly of Fidelity Investments. Walsh had served as a Vice President at Fidelity, where he led blockchain and cryptoasset initiatives, while Carter was Fidelity's first cryptoasset analyst and also co-founded Coin Metrics. Per Axios, the firm launched with around $30 million secured from backers including former Fidelity colleagues and executives at Highland Capital Partners, with a mandate to make both equity investments and token acquisitions.
Castle Island Ventures also operates a crypto-focused podcast, with episodes continuing into 2026. The account has published 134 posts and has been followed by 8,888 accounts. Castle Island Ventures has been mentioned by 272 accounts a total of 642 times.
Castle Island Ventures's portfolio includes BOB, Maple, Flipside, BlockFi, Crusoe, Casa, Halborn and CoinMetrics.io.
Who follows Castle Island Ventures on X?
The accounts that follow Castle Island Ventures include 331 founders, 96 angel investors, 103 influencers and 22 VCs. Among them are Nic Carter, CoinDesk, Hasu, David Hoffman, Db and Loomdart.