Stephen Marcus

Experienced founder of seven companies and venture capitalist. Will work for great coffee.

[Stephen Marcus @smarcus]

@harris Based on what metric ?

[Stephen Marcus @smarcus]

@juliadewahl Congrats Julia !!

[Stephen Marcus @smarcus]

@wolfejosh Excited to be in this one together 🚀🛰️

[Stephen Marcus @smarcus]

John was a mentor of mine. Giant loss for the industry, world.
https://t.co/W8FrBtgzOz

[Stephen Marcus @smarcus]

@PeterJ_Walker This makes sense — some investors will feel pot committed on a large seed. Would love to see the strength of the Series A - large/small, inside or outside lead. That would give more clarity on the types of Series A rounds versus just the probability of one happening.

[Stephen Marcus @smarcus]

@KipMock 🙌🏻

[Stephen Marcus @smarcus]

Been a believer since day zero. Obviously, we would lap the field and win. Congrats @isaiah_p_taylor and the @valaratomics team. Absolutely momentous occasion!! 🚀

[Isaiah Taylor - making nuclear reactors @isaiah_p_taylor]

Today, Valar Atomics became the first startup in history to split the atom.

Announcing Project Nova, a series of zero power critical tests on Valar Atomics' Nova Core in collaboration with Los Alamos NCERC and NNSS.

Nova went critical for the first time this morning at 11:45am.

[Stephen Marcus @smarcus]

Stoked to work with Mo! Working on yet another rocket ship 🚀

[Isaiah Taylor - making nuclear reactors @isaiah_p_taylor]

Excited to announce this morning that Mo Shahzad, former President and CFO of Relativity Space, has joined Valar Atomics as President and CFO.

Valar Atomics is at a major inflection point, and I’m thrilled to have Mo on our team as we take the next steps in our journey.

[Isaiah Taylor - making nuclear reactors @isaiah_p_taylor]

Today we're announcing Valar Atomics' $130m Series A, led by Doug Philippone at Snowpoint Ventures and co-lead by Day One and Dream.

Also joining Team Valar are Balerion, Contrary, DTX, Alumni, Crosscut, Triplepoint, Palmer Luckey, Shyam Sankar, and more great funds and angels.

[Stephen Marcus @smarcus]

Absolutely fired up 🚀 to lead this round with @GVteam @Lux_Capital! World’s best kept secret that Endurosat is one of the largest producers of satellites. Elite team, world class engineering and tech.

[EnduroSat @EnduroSat]

New Scale. More Capacity.

We've secured $104M to scale satellite production to 2 ESPA-class satellites/day. Proud to welcome @RiotVentures, @GVteam, @Lux_Capital, the @EU_EIC Fund & @shrugVC on our mission to streamline access to space data.

More: https://t.co/vSlskNeA4q

[Shawn Ryan @ShawnRyan762]

I never thought I’d have a UFO sitting on my lawn. 😂

Shield AI has just unveiled their new AI-piloted fighter jet, the X-BAT. This Thursday, I’m joined by Shield AI’s Co-Founder and former Navy SEAL, Brandon Tseng, who breaks down the X-BAT in full detail. This autonomous fighter jet has a 2,000-mile range, is the world’s first AI-piloted fighter that doesn’t require a runway, and can take off and land vertically. This is one of those moments that makes me proud to be an American. Brandon also shares insight into other autonomous systems Shield AI has developed—systems already in operational use, including supporting the Coast Guard on counter-narcotics missions.

@shieldaitech
@brandontseng2

[Shield AI @shieldaitech]

Earth is our runway.

Introducing X-BAT, the world’s first AI-piloted VTOL fighter jet. With vertical takeoff and landing, long range, and full autonomy, X-BAT delivers combat power anywhere, anytime. This is the future of airpower.

Watch the video: https://t.co/flfNrRS4L2

Autonomy for the world. The greatest victory requires no war.

#XBAT #Autonomy #NextGenTech #Airpower #Aircraft #Aviation #Defense

[Isaiah Taylor - making nuclear reactors @isaiah_p_taylor]

Valar Atomics has broken ground with Kiewit!

So grateful to the Valar Team, the State of Utah, and the people and leadership of Emery County for their close partnership to make this happen.

Onward!

[Homeland Security @DHSgov]

A great American.

[James Woods @RealJamesWoods]

This is what they destroyed today. I am so heartbroken, I can’t speak.

[Stephen Marcus @smarcus]

@isaiah_p_taylor +1

[Blue Water Autonomy @BlueWaterShips]

We are proud to announce our Series A. @GVteam and @davemuni - with all Blue Water insiders joining - have led a $50M round that allows us to deliver for our customers and our country. 🇺🇸

We are not slowing down.

We have used the last year to hire the best robotics engineers in Boston, build a team of veteran shipbuilders, and open a third office in Washington D.C. We are testing on the salt water on ship-scale hardware. We are building capability to attack America's shipbuilding crisis at its core.

This round allows us to build our first full ship and keep pace with a Navy customer that demands speed. We will double down on our fully autonomous design, deepen relationships with our 50+ suppliers, and deliver mass-producible ships to the U.S. Navy and future customers.

Thanks to our incredible employees, their families, and to our investors. All of us know this is only an early chapter in the story of America's maritime industrial renaissance. Much work lies ahead. 🛠️

Damn the torpedoes.

@Sethwinterroth @smarcus @rylanhamilton @Turnip #shipbuilding

[Stephen Marcus @smarcus]

@JoshuaSteinman My kids do it at a school in LA every morning. There’s hope

[Austin E Gray @AustinEGray]

⚓️🤖 @USNavy just revealed4⃣x very important nuggets about the unmanned fleet, captured by @USNINews

BUT @samlagrone missed some of the most important context.

Here's my summary of the new public info + analysis of what USNI missed:

1⃣ Navy shifting from optionally manned ships to fully unmanned.

Optionally manned "creates a lot of other requirements and cost and complications." - CAPT Matt Lewis

Matt is right, and this is huge.

Six months ago, a senior admiral was on stage at Surface Navy Association saying effectively autonomous = unmanned = attritable = optionally manned.

Now Navy is letting companies choose to build fully unmanned.

2⃣ Enlisted Training: The first cohort of Robotics Warfare Specialists completed A-School training at @CarnegieMellon

The Navy is developing its own school house, but relying on robotics expertise at CMU, MIT, and other great American institutions for speed in the interim

3⃣ Officer Training: Navy is developing a "SWO-Unmanned" officer pipeline.

RADM Trinque N96 compared it to the SWO-Nuke pipeline.

"This has to be mainstream"

4⃣ Navy will deploy an unmanned ship next year as part of a carrier strike group. If this isn't proof that unmanned can become mainstream... I don't know what is?

🤔Austin's Analysis: This is a good piece by USNI capturing some recent developments in Navy SWO and Unmanned communities.

But, it misses perhaps the lynchpin of the Navy's strategy:

💨⏩ Buy. These. Boats. Fast.

If Navy was taking a traditional, slow, COST+ MDAP approach to procuring the unmanned fleet, it would take a decade or more for this fleet to arrive.

In an era of tight budgets and urgent geopolitical threats, only the lean, fast, iterative acquisition approach that Navy seems to be taking can buy many unmanned vessels quickly and affordable.

Reporters may not like covering acquisition reform because it's not sexy. But it must be said. This is how we fix shipbuilding.

[Stephen Marcus @smarcus]

Let’s go! Congrats !!!

[Isaiah Taylor - making nuclear reactors @isaiah_p_taylor]

Valar Atomics is honored to announce that we've been selected by the Department of Energy to achieve criticality on American soil by July 4th, 2026, pursuant to Executive Order 14301.

We're grateful to President Trump and Secretary Wright for their leadership in this matter. 1/x