Back to Part I

    Investment Thesis

    Guillaume Roux-Romestaing

    San Francisco, California — January 2026


    Part II — Why I Invest

    Investing is a side-project for me. Until it's not.

    I want to help those who build the future.

    I invest in folks I know I can help (network, expertise).

    I invest in folks whose startup I would join full-time when the time is right.

    My Edge

    Operator, not career investor. I sit inside a YC company in SF, I build AI GTM systems daily. I host hackathons, I meet founders 3x or 4x per day. I've watched a company scale from pre-seed to $74M raised. I see what winning & losing looks like from the inside, and I know what early signs of it feel like in a founder.

    I'm also quite relatable to entrepreneurs: I straddle their world and that of an investor.

    How I Help

    "Mama, I'm helpful."

    I've become increasingly helpful to founders over the years. This is leading to a positive feedback loop.

    My expertise lies in all things commercial (sales, growth, marketing, partnerships etc.). I also am pretty skilled at building & deploying AI systems for growth. You should see my setup…

    I KNOW A GUY.

    I have 150 investors in my syndicate (all founders, operators) with varied expertise. I'm also pretty good at mapping my network of thousands of VCs, customers, angels.

    You need Uranium? I know a guy.

    M&A lawyer? I know a gal.

    A gun asap? yep..

    Expertise on tubular space manufacturing? yessir.

    Beyond capital, I offer a broad network across VCs, family offices, and angel networks. I can make warm intros and help founders get the best reach. I maintain a full library of fundraising, finance, legal, GTM, growth, and virality playbooks, plus a curated database of 1,000+ funds.

    Access & Deal Flow

    My deal-flow is reactive at the moment: most of my attention is on building, not sourcing deals. It comes primarily from people I know and trust who introduce me to brilliant entrepreneurs. I am fortunate to be seen by my peers in Europe and the US as someone who has lots of connections & relevant views. Some of my dealflow also comes from my social media presence (euro-maxxing), although the volume-to-quality ratio is inverted.

    I get to spend time with founders & measure their intensity when they join my SF Adrenaline Club.

    I scout for a16z. They are the fund that I align with the most in regards to how they view the world, and how they see investing & helping founders. They're also a behemoth, which makes life easier for everyone involved.

    Shoutout Gabriel Vasquez & Angela Strange from Andreessen for the vote of confidence.

    I practically always win deals. After all, it's a bit of a no-brainer: I'm not annoying, my cheque size is very small, the a16z brand helps massively, and my expertise + network offering is worth a lot of gold.

    I currently invest from my syndicate ($100,000 cheque size), a16z ($10,000 cheque size) and my own money when I know the founder well.

    Social Media

    I run half a dozen social media accounts (including secret ones). I mostly use my social media for distribution.

    The aim is to have 100k followers by the end of 2026, so I can promote anything, including my portcos. Inshallah end of 2027: 1M followers.

    As of January 2026:

    IG & TT: 0 followers

    LinkedIn: 2,000 followers

    As of May 2026:

    IG: 8,000 followers

    LinkedIn: 7,000 followers

    The Bridge

    I help European founders build at home or in the US. I speak the language of both ecosystems: literally (French/English) and figuratively (European technical depth + Silicon Valley speed).

    Track Record

    30 investments. 5 graduating to breakout stage, 3 exited.

    Highlights

    Fundamental Technologies15x paper return · pre-seed → $1.2B
    Libra6x realized exit
    DepthFirstpre-seed → $580M Series B
    White Circlepre-seed → $500M
    11x (employee)pre-seed → $350M Series B
    See more →

    Evolution

    2020–2023Haphazard investments. No dealflow. No taste. Not helpful.
    2023–2025Syndicate built. Poor quality dealflow. No taste. Not helpful.
    2025–2026a16z scout. Great dealflow. Improving taste. Somewhat helpful.
    From 2026Great dealflow. Good taste. Very helpful.

    Next step: insane dealflow. Flawless taste. Most helpful.

    The Regret Test

    I don't measure my portfolio by returns. I measure it by regret.

    I don't regret backing now-dead companies where the founder was brilliant. I will back them again on their next venture. There are a bunch of companies I invested in which I regret: part of the learning curve.

    What I'm Building Toward

    I want to help great founders build insanely successful ventures. I do this best right now by becoming the best operator & founder I can be. In the future, when I'm done tinkering (I enjoy launching AI businesses) & cosplaying operator, I want to join a great fund.

    I also see myself investing in later stages, as my portcos graduate, and my network grows.

    I want to own the stars.

    This is my thesis as of January 2026. It will evolve. The core won't: bet on people, not markets. Help founders as best I can. Trust my own read.