Teddy Citrin

Founder of Definition

[Kathleen McMahon @kath_mcmahon]

New biological threats are inevitable, but their impact depends on what we build now.

Our latest technical brief covers the first steps towards resilience: identifying an emerging threat, detecting signs of engineering, and assessing possible geographic origins.

[Alexandr Wang @alexandr_wang]

i forgot about this until @ScottWu46 reminded me, but back in january 2017 when we were 19, scott and i had lunch in SF

at lunch, we talked about how our IMO/IOI/math competition gang could be the next paypal mafia. i knew the competition kids were geniuses by any standard, and felt confident in time we could take the tech world by storm

fast forward nearly 10 years later, and many of our friends from that time are some of the most exciting people in AI and technology (@ScottWu46, @akshat_b, @chameleon_jeff, Jerry Ma, @randomjohnnyh, @0xShitTrader, @stevenkplus1, @thejessezhang, @vickie_ye_, @alexwei_, @demi_guo_, @d_m_ziegler, @hughbzhang, @_mohansolo, @MarkSellke, and many others i'm sure i'm forgetting)

i'm now at that age where i reminisce about everyone i grew up with, and i've known most of these people since middle school (via MATHCOUNTS!). even though we were scattered around the country, we would gchat about math problems and hang out on AoPS, then we did math/algo camps together, and then we did internships together.

very crazy to think about the degree of sheer brilliance of this group when we were just teenagers, and so special to see so many go on to leave their mark on the world.

note to parents: if your kid is on gchat all day solving math problems with some anonymous group of cross-country asian kids, (s)he may just turn out alright.

[Yash Patil @ypatil125]

Applied Compute update:

- crossed ⁠$100M annualized revenue run rate up from zero 18 months ago
- raised $350M at $3.25B led by Elad Gil
- 40% of customers use AC for both custom model training + production inference
- inference serving 1T tokens a day after launching 12 weeks ago
- 2X enterprise customers since last raise
- 3X team since January, 85% are researchers and engineers
⁠- Working with customers like Microsoft, Shopify, Harvey, DoorDash, Cognition, Clay, Decagon and others

To move even faster we need people who are extremely technical AND extremely practical. If this is you, please reach out.

[Cognition @cognition]

Today, Cognition is acquiring @corridor.

Securing the world’s software is the most important problem in technology today.

Let’s get to work!

[Moin Nadeem @moinnadeem]

Introducing Phonic-1, the most advanced speech-to-speech model for agentic tasks — from @phonic_co, the speech-to-speech model company.

We’ve had a breakout year and raised a $27.5M Series A led by @firstround with participation from @Lux_Capital, @felicis, and Definition.

[Cognition @cognition]

We are entering a new dark age of cybersecurity. Devin is here to help.

Introducing the new Devin Security: powered by Claude Mythos and frontier cyber models, plus hundreds of millions of dollars of credits to help teams find, prioritize, and fix urgent vulnerabilities.

[Benjamin F Spector @spectorb]

Hello again, it's been a while.

We're writing to let you know that we have raised quite a lot more money. We're letting you know because we are on the lookout to hire smart people and this will help us do that.

See you again when we have a product or have raised more money!

[Flapping Airplanes @flappyairplanes]

We’ve spent the past year developing new primitives for GPUs. We believe this enables new algorithms to change how machines learn, open new markets, and dramatically reshape AI’s cost structure.

We have raised a $1 billion Series A, co-led by Index and Lux.

[Applied Compute @appliedcompute]

Introducing Shift-1, a frontier coding router trained on AC2 that reduced coding agent cost by up to 55% with no noticeable drop in quality. Try it at https://t.co/089IMPbtAl.

[Greg Brockman @gdb]

towards acceleration of drug development, an extremely exciting and promising emerging application of our models

[Mark Chen @markchen90]

Excited to welcome Orchestra Bio and @ashokaraj_ to OpenAI as we broaden our work in AI-assisted drug discovery!

[Ashoka Rajendra @ashokaraj_]

Four years ago to the day, we started Orchestra Bio to help biotech and pharma teams advance their drug development programs. AI has now reached an inflection point where people and agents can take this on together. Today, we’re thrilled to share that Orchestra Bio is joining OpenAI to continue our mission at an even greater scale.

[OpenAI @OpenAI]

We’ve acquired Orchestra Bio, a platform that helps biopharma teams coordinate the complex process of drug development.

Together, we’ll build on Rosalind, our AI models and tools for life sciences research, to streamline those operations and help new treatments reach patients sooner.

Welcome @ashokaraj_ and team!

https://t.co/vi51OhznQn

[Bob McGrew @bobmcgrewai]

We started Arda in 2025 to speed up American manufacturing. We have spent the last year building with Anduril as our design partner. Today we are launching the company publicly on CNBC and announcing our Series A: $160M at a $1.5B valuation.

Our platform helps manufacturers design and operate manual assembly lines, putting designs into production faster now. Next we'll build automated lines that can be reconfigured as quickly as human workers, letting America make products that now require armies of workers in Asia.

[Eric Glyman @eglyman]

Today, Ramp raised $1.85B at a $60B valuation.

Seven years ago, Karim and I wrote our mission on a Post-it: “Save companies time and money.”

Our mission hasn't changed. It’s just gotten bigger.

[Modal @modal]

Today we're announcing that Modal has crossed $1B in annualized run rate, as well as raised a $750M Series D at a $15.75B valuation, led by @Accel.

Since our Series C, usage has tripled and we’ve grown more than 15x year-over-year.

We are deeply grateful to the developers and companies building on Modal. There's still so much more to build, and we can't think of a better time to be building software.

[Erik Bernhardsson @bernhardsson]

https://t.co/nByTwj2JPX

[Eric Glyman @eglyman]

https://t.co/SGu5SRww1P

[Teddy Citrin @tcitrin]

🟢🟢🟢

[Hone @hone]

Today Hone launches Engines: AI that owns business outcomes.

Chatbots give answers. Agents do tasks. Engines deliver outcomes, and we hold them responsible for creating real value, measured in actual dollars instead of tokens or vibes.

You point it at a business metric, and the Engine figures out the rest. It onboards itself, builds the necessary agents, skills, and memories, collaborates with the right people, and gets better with experience.

From AI leaders to global enterprises, our customers have already used Engines to:

• Uncover millions in procurement savings
• Optimize product funnels
• Manage credit risk
• Increase qualified pipeline in new territories
• Accelerate implementations and improve account management

To scale this impact across the economy, we’ve raised a $60M seed led by Benchmark and Index with participation from Elad Gil, Hanabi, Definition, Diffusion, Lux, SV Angel, and Align.

AI’s raw capabilities are far ahead of the value it creates in the real world, and Engines will help close the gap.

Here’s how they work…

[Noah Shinn @noahrshinn]

Native customer service in Instinct

Nobody likes talking to customer service. Instinct should handle those tasks for you.

With Instinct Concierge, we enabled Instinct to make calls on your behalf. Now, we’re taking this a step further. When your Instinct connects with participating businesses on @SierraPlatform and @DecagonAI, the agents will be able to work together to solve your problem with speed, reliability, and safety without making a phone call.

I’m excited to announce that Instinct will be partnering with Sierra and Decagon to bring customer service experiences directly to your personal agent.

Customer service tasks like:
- Troubleshooting your home wifi issues
- Finding out when a delayed package will arrive
- Figuring out why your bill is higher than last month
- Getting clarity on a confusing return or cancellation policy