a16z Ecosystem Partner David Booth: Cosign Splits Endorsements and Lists
a16z ecosystem partner and Cosign co-founder David Booth announced a product revamp: a new mutual interest network page, separating "cosign endorsements" and "list" into two sets of original terms, changing from an invitation system to a nomination system, and launching a new onboarding process. Priority will be given to those who have filled out the questionnaire.
Cosign was initiated by Booth and a16z general partner Erik Torenberg, positioning itself as a curated professional network for entrepreneurs, combining elements of a wiki-style directory, LinkedIn, and early AngelList. Its goals include directories for investors, companies, and operators, as well as an endorsement map of "who has shaped your career, who is willing to collaborate again, and who will be seen as future stars." Joining requires either an endorsement or a direct application. The two had conducted a similar experiment about seven years ago, which did not succeed.
The new rules categorize endorsements into three types: those who will become stars, those who have shaped your career, and those willing to collaborate anywhere. The list is akin to a playlist or collection board, which can include people, companies, and products, such as "designers willing to collaborate," with a weaker signal than formal endorsements. The team clearly does not want endorsements to be casually given to strangers. Nominators and nominees will be displayed on personal homepages.
The network page is used to see which mutual friends are endorsing which people and companies. The data side aggregates public financing, job changes, and public posts, claiming that even unregistered users can browse some profiles to alleviate cold start issues. The product also plans private intentions: willingness to invest, hire, or collaborate, with connections made after mutual matching. Officials state this is a community rather than a company looking to monetize.
Partners from a16z and former LinkedIn employees discussed the logic in a podcast: after AI turns applications and pitches into massive noise, the signal of real people willing to publicly endorse will become rarer. Job postings on LinkedIn can receive thousands of replies, and the cost of filtering increases after agents amplify them, making the endorsement map a next-level filter.
The buy side consists of entrepreneurs and investors looking for people, projects, and credible endorsements; the sell side includes incumbents willing to label private reputations into three categories. Funding is not currently reflected as transaction commissions but as relationship graphs and discovery rights concentrated in a16z ecosystem tools. Beneficiaries are those already in the map, visible to mutual friends; those under pressure are generic professional social networks relying on self-filled resumes for traffic and outsiders who cannot enter the nomination queue. The event-driven aspect comes from changing the rules in the first week after launch, using tightened original terms to prevent endorsement devaluation.
Source: Public Information
ABAB AI Insight
Booth's path crosses early AngelList, Carta, On Deck, Blackbird, and then to a16z's ecosystem. On Deck once turned "putting people in the same training camp" into a tradable social density; Cosign moves that density from courses to a permanent map: not selling courses, just solidifying who is willing to sign for whom. Torenberg simultaneously combined media, community, and funds, and in a seven-year-old email experiment, someone had pointed out a young engineer still at Tesla at the time, who later went to Cognition—product narrative deliberately connects to this "early discovery" memory.
Capital mobilization is not about opening a new recruitment fund but rather integrating a16z's existing LPs, founders, media, and podcast traffic into the same graph. The form of money is attention and matching rights: those appearing under the "will become stars" label are more likely to enter private chats for financing, hiring, and collaboration. The strategy is to capture a more expensive reputation infrastructure after resumes and agents flood LinkedIn.
Similarities include early AngelList's co-investment relationships, the writing style of LinkedIn recommendations before inflation, and the implicit signals of "who was in the same batch" in the Y Combinator directory. Cosign is in the early stages of expanding from a closed community to a browsable directory, not yet turning the intention network into a closed transaction loop, first controlling who has signing authority.
This is a transfer of pricing power. The price of professional reputation is no longer determined by the positions filled out by individuals but by others willing to publicly pledge their names using three fixed phrases. The mechanism is: generative harassment drives weak signals to zero, strong endorsements become quotas; the platform creates scarcity by splitting original terms and using a nomination system, then sells that scarcity back to the same group of funders looking for people.
ABAB News · Law of Cognition
After noise becomes the sea, signatures are more valuable than resumes
To preserve relationships, first categorize labels into three types
Who has the right to nominate sets the market price