Looking for a co-founder? Don’t draw from this pool

When people choose their cofounder, it’s rarely scientific. They’re guided by trust, and trust is easiest to find in familiar places: former coworkers, college classmates, close friends, people who already sit in your orbit.

While starting a company is chaotic enough without bringing strangers into the mix, I wanted to understand whether this instinct toward familiarity actually comes with a cost. Turns out it does.

Having worked with hundreds of early-stage startups as founders and investors, including at Coatue, Kleiner Perkins, and NFX, we wanted to test whether the instincts founders use to choose partners actually hold up in the data. We surveyed nearly 350 U.S. tech IPOs and more than $1 billion in exit outcomes over the past 20 years to complete the Outcast Billion-Dollar Founder Study. This report analyzes founder count, prior relationships, startup experience, age at founding, and more. We then compared these variables against exit valuation and time to liquidity, linking verifiable founder histories to performance outcomes.

The pattern became clear. Deliberate teams outperform convenient ones, meaning familiarity correlates with worse exits. To put it into hard numbers, founders who had worked together before starting a company produced 21% lower exit valuations than founders who hadn’t, while founders who went to school together saw 7% lower valuations than founders who hadn’t.

When the default is proximity, a founder isn’t deliberately finding the teammate who fills their gaps. Instead, they are selecting for comfort, and comfort doesn’t always produce results. Sharing a relationship built over years in the same class or company means shared perspective and overlapping blind spots. Pre-existing social relationships also make hard conversations—equity splits, role clarity, performance expectations—even more challenging.

What did correlate with stronger exits? Startup experience.

Founders who had previously worked at a startup (even one that failed) produced 41% higher exit valuations than first-time founders. Prior exits were the strongest signal in our study as those with a previous exit achieved 91% higher valuations than those without.

Previous founders know when to hire, when to cut burn, when to push versus sell. Clarity in these pivotal moments doesn’t come from deliberating with a confidant from your past job. It comes from pattern recognition earned the hard way. 

Across the dataset, founding teams outperformed solo founders on both exit size and speed. Adding founders doesn’t guarantee success, but across two decades of venture-backed outcomes, teams show a consistent structural advantage. Even in the current AI cycle, the most valuable private companies were team-founded: OpenAI, xAI, Perplexity AI, Decagon, and Anduril. These teams formed in many ways, some through prior collaboration and others through new introductions, but the consistent pattern is that the largest companies are rarely built alone.

Deliberate teams look different

The founders behind OpenAI, Chime, Decagon, and Uber did not default to whoever was most convenient. Many met through introductions, conferences, and general field overlap. They selected for experience relevant to the problem, not pre-existing familiarity.

Some solo founders will build massive companies. Some college friends will create generational outcomes. It’s true that success can be built in several ways. But it is clear that the median outcome is worse when founders default to what’s easiest.

If you’re forming a founding team, consider these three steps:

• Define the gaps before you define the people. What experience is missing from your own background? Have you scaled a team? Navigated a board? Sold a company? Survived a failed one?
• Widen your aperture beyond your existing network. Your network is a starting point rather than the boundary. Ask for introductions, attend industry events, join the Outcast Catalyst program, and deliberately spend time with people outside your immediate circle. The right partner may sit outside your current graph.
• Seek alignment, not proximity. Shared standards, complementary judgment, and willingness to challenge each other are essential while prior proximity isn’t.

Across 350 exits, the signal is clear: founders who selected partners deliberately, based on experience and complementarity, outperformed those who defaulted to convenience. The better question isn’t “Who do I already know?” It’s: who will challenge me when it matters?

That person may not be in your contacts yet. Finding them takes more work than defaulting to what’s familiar, but the data suggests it’s worth it.