Brian Yun, MD

Building an AI-native hospital for chronic care. Founder at Endo Health (a16z @speedrun, @generalcatalyst) · Scout @a16z

[Brian Yun, MD @brianyunmd]

Announcing that I just became an @a16z scout for @speedrun 🧢

It took us 1.5 years to go from nothing to an apartment in SF with a view of the Golden Gate Bridge, shipping code every week, with O1 VISAs and world class investors like @generalcatalyst and @speedrun.

Every unicorn founder I know had someone believe in them before anyone else did. With immigration tougher than ever, this matters even more for international founders like me.

If you're building something that keeps you up at night, I want to hear about it. DMs open. I'll either write you an angel check with a referral to a16z, or give you helpful feedback as a founder / engineer myself.

[andrew chen @andrewchen]

LAST CALL FOR A16Z SPEEDRUN 2026:

you've got two options in life:
1/ build for yourself
2/ build for someone else

(as a wise account once said). Those of you who have been following our work at a16z speedrun have been tracking us bc building for yourself, and betting on yourself, is the highest calling. It's the most fun, you learn the most, and there's a chance to build something great.

this is why you should:
- quit whatever it is you're doing
- build the startup you've wanted to build
- work with me and the a16z team 1:1
- And yes, I'll invest up to $1M via a16z speedrun
(and the earlier your startup, the better. apply here: https://t.co/DZZmyTm1iQ)

In fact we are entering the final 72 hours before the deadline Sunday Sep 28 2025, 11:59PM PST.

the details:
- easy/quick to apply
- we wire immediately
- up to $1M of investment
- hosted at a16z HQ in SF SOMA
- 12 week program, with an IRL kickoff
- private dinners/Q&A with Marc/Ben of a16z
- live events with the founders of Carta, Zynga, DoorDash, Behance, Airtable, Twilio, Figma, and more

there's a lot more to the program that's on our website, and you can check out the FAQ for more.

Some common questions that come up:
- do you accept global founders? YES
- do you accept solo founders? YES
- do you need to be technical? NO
- do I need a referral? NO

in general, anyone can apply. But the ones that are selected need to stand out. If you don't have a cofounder, that's fine -- but have you recruited a few people to be a team? Do you have some customers? Those are all useful to demonstrate that you're serious, and you've been able to start the first steps of your journey by convincing other people to join you. Are you international? Great -- we'll help you with relo and O-1 visas. Not technical? That's fine, but then tell us the prototype you vibecoded, or the engineer you recruited.

How we're different
Sometimes we're asked how we designed speedrun to be different. There's a lot of ways:

- we're part of a16z, a broader firm with a big network, lots of vertical expertise, and a long track record

- we have a deep operating team, with experts from talent, people, BD, creators, marketing, and so on. We've invested big here and help

- we host speedrun from a16z's offices in SF (for SR6), where you're part of our community of founders

- we're the only multistage firm with a scaled effort to invest in the unique needs of early stage startups. We have a whole team on it and we're working hard!

scouts and referrals
You might have noticed a number of folks announcing themselves as scouts who invest in a16z speedrun companies. If you know them, great! Please reach out.

They are often founders who have gone through the program, and they can give you tips, connect you to folks at speedrun with a warm intro, etc. Sometimes they invest, sometimes they don't :) just ask.

In general, referrals are useful but not required. They are useful in that we get a lot of interest for speedrun and it often takes us a few weeks to work through everyone. (sorry!) Thus, if someone flags your startup to us, we can help prioritize and get to it earlier. But again, not required.

The deadline
Consider this your last call! The final deadline is Sunday 11:59PM PST. Apply to speedrun, we'll get back to you shortly, we wire ASAP, and then we kick off SR6 in SF in Jan 2026.

Here's your chance to bet on yourself.

[Brian Yun, MD @brianyunmd]

@coryalthoff StabilityAI

[Brian Yun, MD @brianyunmd]

@TechEmails ah, remember stability?

[Brian Yun, MD @brianyunmd]

@Tocelot compute per researcher is also what top talents are looking at these days

[Brian Yun, MD @brianyunmd]

@cremieuxrecueil researchers had viral sense

[Brian Yun, MD @brianyunmd]

@GorryTan shouldve named the account Tarry Gan

[Brian Yun, MD @brianyunmd]

@tmhammer @Tocelot 100%, idea guy with get-shit-done scrappy mindset vs. idea guy with a sense of entitlement

[Brian Yun, MD @brianyunmd]

@michael_chomsky they're just good investors

[Brian Yun, MD @brianyunmd]

@drewlevinn this post gives off delve vibes

[Brian Yun, MD @brianyunmd]

@VCBrags if you don't have fuck you energy then you're ngmi

[Brian Yun, MD @brianyunmd]

@paularambles is this a thirst trap for oai recruiters

[Brian Yun, MD @brianyunmd]

true, twitter is a pretty b2b ish platform overall

[David Im @davidim]

we've hit 20k users in 8 weeks.

~95% of users came from organic content on instagram and tiktok

for people in twitter : if u want to sell to people outside tech, learn to hack ig/tiktok

[Brian Yun, MD @brianyunmd]

@pmarca not so long ago...

[Brian Yun, MD @brianyunmd]

@TechCrunch this should be called out more

[Brian Yun, MD @brianyunmd]

@ns123abc fucking legend

[Brian Yun, MD @brianyunmd]

@BoBrainerd someone should be filming silicon valley rn

[Brian Yun, MD @brianyunmd]

@sabakarimm this is not a hot take at all

[Brian Yun, MD @brianyunmd]

@Polymarket should have made it a job offer. or affordable sf housing prices.

[Brian Yun, MD @brianyunmd]

@signulll daily reminder that we're just a spec of stardust that exist for a split second in the vast history of the universe

[Brian Yun, MD @brianyunmd]

@hyojun_at coincidence? i think not

[Brian Yun, MD @brianyunmd]

@nikitabier @sporadica fucking respect for the product obsession man