a16z’s Erik Torenberg sits down with Josh Elman, Olivia Moore, and David Booth to introduce Cosign, a new product built around professional reputation and the people, companies, and products you’re willing to put your name behind. They unpack a simple idea at the heart of Silicon Valley: some of the most valuable professional signals aren’t credentials, but who believes in you. From the mentor who shaped your career to the colleague you’d work with anywhere or the young builder you think everyone should be watching, Cosign is an attempt to make those signals more visible and durable. They also discuss why human endorsements may become more valuable as AI makes outreach and information abundant, what existing professional networks get right and miss, and how making reputation more legible could help talented people get discovered earlier, find collaborators, and carry the work they’ve done behind the scenes into whatever they do next. Timestamps: 00:00 - Intro 00:53 - What Cosign Is & Why It Exists 07:24 - The Three Signals: Mentors, Investors & Cosigns 10:27 - Building the Anti-LinkedIn: Talent Discovery Redesigned 16:36 - Why Reputation Should Be Granular, Not Generic 22:52 - The Feed: Questions, Announcements & Signal Density 28:41 - The Meme Dynamic: Public Cosigns as Social Capital 36:50 - Existing Platforms: Why LinkedIn & X Fall Short 44:03 - Silicon Valley as Meritocracy & the Power of Being First 49:33 - Closing Thoughts Resources: Follow Josh Elman on X: https://x.com/joshelman Follow Olivia Moore on X: https://x.com/omooretweets Follow David Booth on X: https://x.com/david__booth Follow Cosign: https://x.com/cosign_build Read more about Cosign: https://www.a16z.news/how-silicon-valley-knows-its-people Stay Updated: If you enjoyed this episode, be sure to like, subscribe, and share with your friends! Find a16z on X: https://twitter.com/a16z Find a16z on LinkedIn: https://www.linkedin.com/company/a16z Listen to the a16z Show on Spotify: https://open.spotify.com/show/5bC65RDvs3oxnLyqqvkUYX Listen to the a16z Show on Apple Podcasts: https://podcasts.apple.com/us/podcast/a16z-podcast/id842818711 Follow our host: https://x.com/eriktorenberg Please note that the content here is for informational purposes only; should NOT be taken as legal, business, tax, or investment advice or be used to evaluate any investment or security; and is not directed at any investors or potential investors in any a16z fund. a16z and its affiliates may maintain investments in the companies discussed. For more details please see http://a16z.com/disclosures.