Guillaume Roux-Romestaing
San Francisco, California — January 2026
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.
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.
"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 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.
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.
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.
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).
30 investments. 5 graduating to breakout stage, 3 exited.
Next step: insane dealflow. Flawless taste. Most helpful.
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.
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.
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.