Mark Jeffrey

Mark Jeffrey is a technology entrepreneur, author, podcast host and investor whose documented work spans online communities, business networking, Bitcoin and decentralised artificial intelligence.

Jeffrey co-founded ZeroDegrees, an online business-networking company. IAC’s first-quarter 2004 corporate report records its acquisition of ZeroDegrees and confirms that the transaction had closed. Proof of Talk’s 2026 speaker announcement also identifies Jeffrey as a co-founder of ZeroDegrees and The Palace, an early graphical online community.

Jeffrey subsequently wrote Bitcoin Explained Simply and The Case for Bitcoin. Apple Podcasts dates the books to 2013 and 2015 respectively, correcting the 2014 and 2015 dates used in the previous profile. The same listing identifies Jeffrey as the creator and host of Hash Rate, a technology podcast covering cryptocurrency, artificial intelligence and decentralised infrastructure. Stillcore Capital’s fund overview likewise identifies Jeffrey as the programme’s host and describes its focus as Bittensor and decentralised AI.

In 2016, Jeffrey launched Guardian Circle. A company announcement distributed through GlobeNewswire in October 2018 identifies Jeffrey as its founder and chief executive and describes Guardian Circle as a decentralised emergency-response platform that connected people requesting assistance with nearby trusted contacts.

Jeffrey announced Stillcore Capital in September 2025, naming Jason Calacanis and Rob Greer as partners and describing the fund’s focus as TAO and Bittensor subnet tokens. Stillcore’s dated fund overview listed Jeffrey as Partner and Co-CIO. An amended SEC Form D dated 27 April 2026 separately names Mark Jeffrey as an executive officer and managing member associated with Stillcore Capital Fund II. A July 2026 announcement concerning an advisory appointment continued to identify Jeffrey as a partner at Stillcore Capital, but did not repeat the Co-CIO designation. Partner is therefore the strongest-supported current public title.

For Proof of Talk Paris on 2 and 3 June 2026, the organiser publicly billed Jeffrey as Partner at Stillcore Capital. The supplied first-party session record states that Jeffrey moderated two Bittensor-track discussions, one addressing the relationship between decentralised intelligence, AI and Bitcoin, and another examining how Bittensor infrastructure could support operating businesses.