Sourcery

Justin Fishner-Wolfson is Co-Founder and Managing Partner of 137 Ventures, the firm that turned a contrarian read on private markets into a $15B platform and one of the largest SpaceX positions in venture. His firm now owns more than 1% of SpaceX, a stake worth roughly $20B at the company's $1.77T listing valuation.
He was on the SpaceX deal team at Founders Fund in 2008, left to start 137, and has since bought into the company roughly two dozen times, mostly through secondaries and tenders, without selling a share. He has been buying since SpaceX was valued at $1B. In this conversation he walks through the thesis that companies would stay private longer, why partial liquidity sharpens founder focus rather than dulling it, and how 137 concentrates capital in durable companies instead of chasing sectors.
We cover SpaceX's shift from cost-plus to fixed-price economics, the Falcon 9 reusability that made launch profitable, when Starlink became underwritable, the $240B secondary market, why he backed Cognition over the foundational models, his cash on cash discipline over ownership targets, and what he plans to do with the stake once the lockup lifts.

Justin Fishner-Wolfson: https://www.linkedin.com/in/justinfw
Molly O’Shea: https://x.com/MollySOShea 
Sourcery: ⁠https://x.com/sourceryy 

𝐄𝐏𝐈𝐒𝐎𝐃𝐄 𝐋𝐈𝐍𝐊𝐒
YouTube: https://youtu.be/y_JN4WNu8JY

𝐒𝐏𝐎𝐍𝐒𝐎𝐑𝐒
• Brex—The modern finance platform, combining the world’s smartest corporate card with integrated expense management, banking, bill pay, & travel. https://brex.com/sourcery 
• Turing—Turing delivers top-tier talent, data, and tools to help AI labs improve model performance—and enables enterprises to turn those models into powerful, production-ready systems. https://turing.com/sourcery 
• VCX—VCX is the public ticker for private tech, allowing investors of all sizes to invest in venture capital. View The Portfolio at http://GetVCX.com  
• Deel—Deel is the global people platform that helps startups hire, manage, pay, and equip anyone, anywhere. Trusted by more than 35,000 fast-growing companies, Deel is the people platform that just works, so teams can scale without the chaos. Visit: https://www.deel.com/sourcery
• Public–Investing platform Public just launched Generated Assets, which lets you turn any idea into an investable index with AI. With Generated Assets, you can build, backtest, refine, and invest in any thesis with AI. Gone are the days of one-size-fits-all ETFs. https://public.com/sourcery 
• Merge—The leading provider of customer-facing integrations and agentic tools for frontier LLMs, Fortune 500 organizations, and B2B SaaS companies. Visit https://merge.dev  
Follow Sourcery for the latest updates!
https://www.sourcery.vc

Disclosure
Paid Endorsement. Brokerage services by Open to the Public Investing Inc, member FINRA & SIPC. Advisory services by Public Advisors LLC, SEC-registered adviser. Crypto trading provided by Zero Hash LLC, licensed by the NYSDFS. Generated Assets is an interactive analysis tool by Public Advisors. Output is for informational purposes only and is not an investment recommendation or advice. See disclosures at public.com/disclosures/ga. Matched funds must remain in your account for at least 5 years. Match rate and other terms are subject to change at any time.
 
𝐓𝐈𝐌𝐄𝐒𝐓𝐀𝐌𝐏𝐒
(00:00) Justin Fishner-Wolfson, Co-Founder & Managing Partner at 137 Ventures
(00:51) The story of SpaceX
(02:50) Why companies are staying private longer
(04:15) What Liquidity actually means for Founders and Employees
(05:38) Why he left Founders Fund to start from scratch
(06:23) $240B Secondaries market
(07:01) What made SpaceX a generational bet
(07:52) How the Falcon 9 made the entire Space Industry obsolete
(10:59) When Starlink became the obvious winner
(13:29) How 137 Ventures turns Conviction into Compounding
(14:09) Backing SpaceX alumni: the Impulse investment
(14:32) Will the secondary market keep growing?
(15:15) Companies vs. Categories

Brian Singerman spent 17 years at Founders Fund, where he helped drive large concentrated investments into companies like SpaceX, Palantir, Airbnb, Stripe, Stemcentrx, Anduril, and Affirm. He recently left to co-found GPx, a new fund backing emerging managers. In this episode we break down the philosophy behind Founders Fund's concentration strategy, how a lifetime of competitive strategy gaming shapes the way he reads founders, and why he is now applying the same framework to GPs instead of companies.
"When I did get to meet Elon and learn more about SpaceX, it was extremely clear that there was nobody else like him on the planet who could actually pull something like SpaceX off."
The conversation runs from his 2008 start at Founders Fund and what he learned from Peter Thiel, to the SpaceX bet the firm staked its career on, why he has never read a financial report, and his read on genuinely authentic founders like Cyan Banister, Palmer Luckey, and Alex Karp. Plus a round of questions submitted by Max Levchin, Trae Stephens & Scott Nolan, his views on wealth taxes and asset seizure, and his bet on N-of-1 human cultural artifacts.

Brian Singerman: https://x.com/briansin 
Molly O’Shea: https://x.com/MollySOShea 
Sourcery: ⁠https://x.com/sourceryy 

𝐄𝐏𝐈𝐒𝐎𝐃𝐄 𝐋𝐈𝐍𝐊
YouTube: https://youtu.be/Il5dCTkIF_M

𝐒𝐏𝐎𝐍𝐒𝐎𝐑𝐒
• Brex—The modern finance platform, combining the world’s smartest corporate card with integrated expense management, banking, bill pay, & travel. https://brex.com/sourcery 
• Turing—Turing delivers top-tier talent, data, and tools to help AI labs improve model performance—and enables enterprises to turn those models into powerful, production-ready systems. https://turing.com/sourcery 
• VCX—VCX is the public ticker for private tech, allowing investors of all sizes to invest in venture capital. View The Portfolio at http://GetVCX.com  
• Deel—Deel is the global people platform that helps startups hire, manage, pay, and equip anyone, anywhere. Trusted by more than 35,000 fast-growing companies, Deel is the people platform that just works, so teams can scale without the chaos. Visit: https://www.deel.com/sourcery
• Public–Investing platform Public just launched Generated Assets, which lets you turn any idea into an investable index with AI. With Generated Assets, you can build, backtest, refine, and invest in any thesis with AI. Gone are the days of one-size-fits-all ETFs. https://public.com/sourcery 
• Merge—The leading provider of customer-facing integrations and agentic tools for frontier LLMs, Fortune 500 organizations, and B2B SaaS companies. Visit https://merge.dev  
Follow Sourcery for the latest updates!
https://www.sourcery.vc

Disclosure
Paid Endorsement. Brokerage services by Open to the Public Investing Inc, member FINRA & SIPC. Advisory services by Public Advisors LLC, SEC-registered adviser. Crypto trading provided by Zero Hash LLC, licensed by the NYSDFS. Generated Assets is an interactive analysis tool by Public Advisors. Output is for informational purposes only and is not an investment recommendation or advice. See disclosures at public.com/disclosures/ga. Matched funds must remain in your account for at least 5 years. Match rate and other terms are subject to change at any time.

Tom Mueller, Founder, CEO and CTO of Impulse Space, (aka Employee #1 at SpaceX) gives Sourcery a walkthrough of the company's Redondo Beach factory, from the avionics clean room to a live rocket engine firing in the vacuum chamber.

As SpaceX's founding employee, Tom led development of the engines for Falcon and Dragon and started the origins of what became Starship. His proudest project, the Merlin engine, still flies Falcon 9. In this episode he explains why he left to build the next layer of space infrastructure: moving payloads and cargo around once they're in orbit.

We tour Mira (the company's precision maneuvering spacecraft), Helios (the vehicle bringing same-day delivery to space), and the Deneb engine, and get into how Impulse designs and builds: extreme vertical integration, 3D-printed engines, in-house composite tanks, and a "build, test, iterate" loop.

Tom also shares where he thinks the industry is heading, on nuclear electric propulsion, data centers in space, the return to the Moon, and what it was like to work with Elon Musk.

Tom Mueller: https://x.com/lrocket 
Molly O’Shea: https://x.com/MollySOShea 
Sourcery: ⁠https://x.com/sourceryy 

𝐄𝐏𝐈𝐒𝐎𝐃𝐄 𝐋𝐈𝐍𝐊𝐒
YouTube: https://youtu.be/WIORHdlPWAI

𝐒𝐏𝐎𝐍𝐒𝐎𝐑𝐒
• Brex—The modern finance platform, combining the world’s smartest corporate card with integrated expense management, banking, bill pay, & travel. https://brex.com/sourcery 
• Turing—Turing delivers top-tier talent, data, and tools to help AI labs improve model performance—and enables enterprises to turn those models into powerful, production-ready systems. https://turing.com/sourcery 
• VCX—VCX is the public ticker for private tech, allowing investors of all sizes to invest in venture capital. View The Portfolio at http://GetVCX.com  
• Deel—Deel is the global people platform that helps startups hire, manage, pay, and equip anyone, anywhere. Trusted by more than 35,000 fast-growing companies, Deel is the people platform that just works, so teams can scale without the chaos. Visit: https://www.deel.com/sourcery
• Public–Investing platform Public just launched Generated Assets, which lets you turn any idea into an investable index with AI. With Generated Assets, you can build, backtest, refine, and invest in any thesis with AI. Gone are the days of one-size-fits-all ETFs. https://public.com/sourcery 
• Merge—The leading provider of customer-facing integrations and agentic tools for frontier LLMs, Fortune 500 organizations, and B2B SaaS companies. Visit https://merge.dev  
Follow Sourcery for the latest updates!
https://www.sourcery.vc
Disclosure
Paid Endorsement. Brokerage services by Open to the Public Investing Inc, member FINRA & SIPC. Advisory services by Public Advisors LLC, SEC-registered adviser. Crypto trading provided by Zero Hash LLC, licensed by the NYSDFS. Generated Assets is an interactive analysis tool by Public Advisors. Output is for informational purposes only and is not an investment recommendation or advice. See disclosures at public.com/disclosures/ga. Matched funds must remain in your account for at least 5 years. Match rate and other terms are subject to change at any time.

𝐓𝐈𝐌𝐄𝐒𝐓𝐀𝐌𝐏𝐒
(00:00) Tom Mueller, Founder, CEO & CTO of Impulse Space
(00:49) Inside Impulse Space
(02:32) Avionics Bay floor
(02:59) Building rockets at home
(03:50) Mira and Helios
(08:00) Why he left SpaceX
(09:33) The Deneb Engine walkthrough
(11:42) Testing in Mojave
(12:23) Favorite part of the Engine
(13:30) How it's 3D Printed
(14:21) Why 3D Printing changes everything
(16:54) Finding Talent for COPVs
(17:28) No Modern hardware without software
(19:52) The Mill Turn explained
(22:42) Payload Deck Design
(25:28) Entering the Secret Area
(30:48) Thrust, Flow Rate, and 100 Sensors
(32:13) Collision avoidance in Orbit
(32:57) The Electric Propulsion Chamber
(34:28) Nuclear Electric is the future
(38:49) Data Centers in Space
(40:28) SpaceX and Starlink's Growth
(41:10) Working with Elon

Eric Romo, President & COO of Impulse Space, joins Sourcery on the company's manufacturing floor in Redondo Beach to break down the freshly closed $500M Series D co-led by 137 Ventures and BANNER VC that pushes Impulse past $1 billion raised.
We get into what the capital actually unlocks (hiring and production, not flashy CapEx), why "space tug" doesn’t cut it for Mira, and how a single successful flight spurred demand from across the industry. Eric explains Impulse's three products — Mira, Helios, Caravan — and makes the case for staged access to GEO against traditional options.
He also gets candid: reality on orbital debris cleanup, why Impulse is "closer to a fighter jet than a tugboat," and the hard lesson from his SpaceX days (he was employee #13; CEO Tom Mueller was #1) that made in-housing manufacturing non-negotiable.

Eric Romo: https://x.com/_Eric_Romo 
Molly O’Shea: https://x.com/MollySOShea 
Sourcery: ⁠https://x.com/sourceryy 

𝐄𝐏𝐈𝐒𝐎𝐃𝐄 𝐋𝐈𝐍𝐊𝐒
YouTube: https://youtu.be/42035XPxgbA

𝐒𝐏𝐎𝐍𝐒𝐎𝐑𝐒
• Brex—The modern finance platform, combining the world’s smartest corporate card with integrated expense management, banking, bill pay, & travel. https://brex.com/sourcery 
• Turing—Turing delivers top-tier talent, data, and tools to help AI labs improve model performance—and enables enterprises to turn those models into powerful, production-ready systems. https://turing.com/sourcery 
• VCX—VCX is the public ticker for private tech, allowing investors of all sizes to invest in venture capital. View The Portfolio at http://GetVCX.com  
• Deel—Deel is the global people platform that helps startups hire, manage, pay, and equip anyone, anywhere. Trusted by more than 35,000 fast-growing companies, Deel is the people platform that just works, so teams can scale without the chaos. Visit: https://www.deel.com/sourcery
• Public–Investing platform Public just launched Generated Assets, which lets you turn any idea into an investable index with AI. With Generated Assets, you can build, backtest, refine, and invest in any thesis with AI. Gone are the days of one-size-fits-all ETFs. https://public.com/sourcery 
• Merge—The leading provider of customer-facing integrations and agentic tools for frontier LLMs, Fortune 500 organizations, and B2B SaaS companies. Visit https://merge.dev  
Follow Sourcery for the latest updates!
https://www.sourcery.vc

Disclosure
Paid Endorsement. Brokerage services by Open to the Public Investing Inc, member FINRA & SIPC. Advisory services by Public Advisors LLC, SEC-registered adviser. Crypto trading provided by Zero Hash LLC, licensed by the NYSDFS. Generated Assets is an interactive analysis tool by Public Advisors. Output is for informational purposes only and is not an investment recommendation or advice. See disclosures at public.com/disclosures/ga. Matched funds must remain in your account for at least 5 years. Match rate and other terms are subject to change at any time.

𝐓𝐈𝐌𝐄𝐒𝐓𝐀𝐌𝐏𝐒
(00:00) Eric Romo, President & COO at Impulse Space
(00:58) Fueling the next phase with a $500M Series D
(04:30) Crossing the $1B funding mark
(06:00) The freedom to execute
(07:09) Why startups die from indigestion
(08:30) Building beyond SpaceX
(13:32) How defense became the real opportunity
(16:19) Impulse’s product stack: Mira, Helios & Caravan 
(23:43) The economics of urgency
(26:23) "Closer to a fighter jet than a tugboat"
(30:40) The new era of space defense
(37:33) The SpaceX DNA at Impulse
(38:27) The biggest lesson from SpaceX
(44:23) Hiring world class engineers
(45:38) If not COO, then what?
(46:43) The road to first Helios launch

Merge co-founders Shensi Ding (CEO) and Gil Feig (CTO) join Sourcery for a wide-ranging conversation on building AI infrastructure that quietly powers some of the biggest companies in tech — including OpenAI, Perplexity, Netflix, Uber, Mistral, and Dropbox.
They break down Merge's three-product suite (Unified, Agent Handler, and Gateway), the make-or-break month that pushed them to rebuild around AI, and why they now believe "English is your programming language." Gil gets candid on the state of AI security — supply chain attacks, agentic code flooding GitHub, and why the scariest threat is always internal. Shensi shares hard-won hiring philosophy (missionaries vs. mercenaries), her admiration for Benioff and the "beginner's mind," and a hot take on companies over-engineering their own models.
Plus: the SaaSpocalypse, the brutal reality of token-maxxing bills, governing employee AI access, headless Salesforce, and whether today's AI valuations make any sense at all.

Shensi Ding: https://x.com/shensi
Gil Feig: https://x.com/GilFeig 
Molly O’Shea: https://x.com/MollySOShea 
Sourcery: ⁠https://x.com/sourceryy 

𝐄𝐏𝐈𝐒𝐎𝐃𝐄 𝐋𝐈𝐍𝐊𝐒
YouTube: https://youtu.be/SjrejHEAdeg

𝐒𝐏𝐎𝐍𝐒𝐎𝐑𝐒
• Brex—The modern finance platform, combining the world’s smartest corporate card with integrated expense management, banking, bill pay, & travel. https://brex.com/sourcery 
• Turing—Turing delivers top-tier talent, data, and tools to help AI labs improve model performance—and enables enterprises to turn those models into powerful, production-ready systems. https://turing.com/sourcery 
• VCX—VCX is the public ticker for private tech, allowing investors of all sizes to invest in venture capital. View The Portfolio at http://GetVCX.com  
• Deel—Deel is the global people platform that helps startups hire, manage, pay, and equip anyone, anywhere. Trusted by more than 35,000 fast-growing companies, Deel is the people platform that just works, so teams can scale without the chaos. Visit: https://www.deel.com/sourcery
• Public–Investing platform Public just launched Generated Assets, which lets you turn any idea into an investable index with AI. With Generated Assets, you can build, backtest, refine, and invest in any thesis with AI. Gone are the days of one-size-fits-all ETFs. https://public.com/sourcery 
• Merge—The leading provider of customer-facing integrations and agentic tools for frontier LLMs, Fortune 500 organizations, and B2B SaaS companies. Visit https://merge.dev  
Follow Sourcery for the latest updates!
https://www.sourcery.vc

Disclosure
Paid Endorsement. Brokerage services by Open to the Public Investing Inc, member FINRA & SIPC. Advisory services by Public Advisors LLC, SEC-registered adviser. Crypto trading provided by Zero Hash LLC, licensed by the NYSDFS. Generated Assets is an interactive analysis tool by Public Advisors. Output is for informational purposes only and is not an investment recommendation or advice. See disclosures at public.com/disclosures/ga. Matched funds must remain in your account for at least 5 years. Match rate and other terms are subject to change at any time.
 
𝐓𝐈𝐌𝐄𝐒𝐓𝐀𝐌𝐏𝐒
(00:00) Shensi Ding & Gil Feig, Co-Founders at Merge
(01:04) Three products. One big bet
(03:20) How Merge made the AI pivot
(04:42) The Classic Innovator’s Dilemma
(05:58) Building culture around AI
(07:10) The leverage nobody’s talking about
(08:52) Codex vs Claude Code
(09:15) The scale nobody knew about
(09:47) SaaS, Finance, and the Biggest AI Labs
(10:46) Why AI companies buy differently
(12:04) What AI sales actually looks like
(13:04) The Fastest sales cycles in the market
(14:35) Why is Cybersecurity broken
(15:59) Merge's solution to agent security
(19:16) Mythos, Wiz, and the GitHub Hack
(22:34) 1,000 Bot signups in one hour
(23:23) Real reason companies pay ransom to hackers
(25:43) The State of AI Infrastructure Costs
(26:41) Internal AI Governance is the next big problem