Cyber-Flâneur 👁✨@gringojobs @bitso @CHANEL
Mexico City & LatAm
Joined June 2009
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super important honest advice to founders. if you are working on a dead end, get out. you don’t owe that to anyone, including investors (who regularly forgive and experience failure, and ideally care more about you doing your life’s work than a subpar outcome)
Foursquare was acquired last month. The outcome was disappointing. It's taken me a while to write this, but I think I'm finally done grieving it. Here are some thoughts on our final years, an effort to honor the team who helped build & maintain FSQ's legacy, and my attempt to finally get some closure. teendrama.substack.com/p/som…
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People who cured / are curing their own cancer on X:
1/ @sytses - bone cancer, billionaire founder of Gitlab, developed 10+ personalized therapies for himself.
2/ @paul_conyngham - shrank his dog Rosie's mast cell cancer tumors after chemo and surgery weren't enough. Now backed by YC and Founders Fund
3/ @miriamgonp - stage 4 breast cancer, tumor sequenced, searching for vaccine manufacturer now
4/ @kevinace - stage 4 lung cancer, angel investor in 300+ companies, first drug stopped working after 18 months. Vaccine designed, now paying $300k out of pocket for the vaccine
5/ @masonbgrant: going founder mode on his his 32-year-old wife's rare liver cancer, sequencing her tumor with AI agents
6/ @ArunRLverma: former product leader at Atoms and Shopify, brain tumor, built a vaccine from his tumor. Now building an AI health agent startup based on what he went through
We're going to make it
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Walmart is selling real diamond earrings for $12.
Not a typo. Half-carat lab-grown diamonds, same carbon, graded by the same labs that grade the stone in your engagement ring. A jeweler can't tell them apart without a machine.
And that $12 price tag is why the company that invented the engagement ring is about to get sold for scrap.
De Beers ran the diamond trade for over a century. At its peak it controlled up to 90% of the world's rough supply, and when demand dipped it just locked diamonds in London vaults until prices came back. The slogan "A Diamond Is Forever" came from their ad agency in 1947. So did the rule that a ring should cost two months of your salary. Before that campaign, most American brides never got a diamond at all.
The whole thing held for 80 years because there were only so many mines. Then China started growing diamonds in reactors, and there's no vault on earth big enough to hide a factory's output.
Lab-grown wholesale prices have crashed roughly 96% from their peak, down to around $100 a carat. The Knot says 61% of engagement rings sold in 2025 had lab-grown center stones, up 239% since 2020. Even De Beers' own average selling price fell 32% in a year, to $105 a carat.
So Anglo American, which owns De Beers, has written it down by $6.8 billion in two years and is now in talks to sell the whole thing for about $1 billion. This is a company that was valued over $18 billion in 2001 and $13 billion as recently as 2011.
The stones coming out of the ground are the same as ever. The only scarce thing De Beers ever owned was the marketing, and marketing doesn't survive a $12 price tag at Walmart.
Readers added context they thought people might want to know
Walmart $12 0.5ct "Created White Diamond" studs (Paris Jewelry) often fail diamond testers per reviews and are not genuine lab-grown diamonds. Certified lab-grown 0.5ct pairs list around $79-89.
walmart.com/ip/14k-White-G…
walmart.com/ip/JeenMata-Ce…
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Andrej Karpathy makes a good point: as AI does more of the work, more of your job becomes reading what it produces.
His first tip caught my eye. Ask the model to explain things in ASD-STE100.
ASD-STE100 is a controlled English standard built for aircraft maintenance manuals. A mechanic anywhere in the world should read a step once and get it right.
The core rules:
1. Keep sentences short
2. One action per step
3. Say who does what
4. Give each thing one name and stick to it
AI output breaks that last rule all the time. It says "worker," then "agent," then "executor," and you can't tell if it means one component or three.
The full spec is strict. Karpathy asks for "80% of the way," and that works for daily use.
Someone turned it into an open-source skill:
github.com/danyuchn/asd-ste1…
We'll be spending a lot more time trying to understand the outputs of language models. A few thoughts, tips & tricks:
Writing. Something I've had success with: Ask your LLM to explain something in ASD-STE100, it's a controlled language specification originally developed for aerospace maintenance documentation. LLMs well-versed in this language and it comes with heavy constraints on clean writing style that I often find a lot more readable. Sometimes I've tried to soften it a bit e.g. ask for "80% of the way to ASD-STE100" because the spec is quite stringent. But even better:
Diagrams / images. Instead of writing, ask your LLM to create a diagram. These can be a lot easier to process, parse, and understand. But even better:
Web pages. Ask for output "in HTML" to get a beautiful, interactive webpage. LLMs are getting really good at frontend and can create beautiful experiences, animations, etc. But even better:
Explainer videos. The output format I am most bullish on is fully custom / bespoke explainer videos generated on any arbitrary topic. Experiment with things like "Create a 3b1b style video explainer on X. Use my ElevenLabs API key for audio narration". (you'd need an API key for the latter or you can ask your LLM to find you decent free alternatives that use your local compute). This is actually starting to work!
In summary:
- As LLMs get better, they will do more and more of the legwork autonomously, and a lot more of our work will rise up the abstractions into oversight and understanding.
- Luckily, LLMs can help here too because as intelligence and code are increasingly abundant, you can ask for large, custom, discardable software artifacts (e.g. web apps, video explainers) that would have never made sense to create before. Push the boundaries here and you'll be surprised.
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We are delighted that $PSUS and $PS are now listed on the Mexican Stock Exchange. We will be visiting our Mexican shareholders next month and look forward to a long-term relationship.
¡Damos la bienvenida a Pershing Square al mercado mexicano!
Nos entusiasma anunciar el listado en el Sistema Internacional de Cotizaciones (SIC) de:
- Pershing Square USA, Ltd. ($PSUS)
- Pershing Square Inc. ($PS)
Con su incorporación, el mercado mexicano amplía las alternativas de inversión disponibles para los participantes.
Desde Grupo BMV, celebramos la llegada de nuevos valores internacionales y continuamos fortaleciendo la conexión de México con los mercados globales.
#GrupoBMV #SIC #MercadoDeValores #Inversión
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Life is a repeat game and an infinite game. People who don't understand this won't win in the long run.
Life is long. Choose to work with good people.
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All-In Summit: Bending Spoons CEO Luca Ferrari
-- Buying product-market fit > building product-market fit
-- How $40,000 left over from a failed startup became the seed capital
-- How a business can run better after most of the staff is gone
-- Why traditional PE can't run Luca's playbook
-- Europe’s overlooked talent pool
++ much more!
(0:00) @luke10ferrari joins the Besties!
(1:56) Crashing an AI startup, the $40,000 restart & buying product market fit
(4:59) The in-house tech stack, shrinking the teams & the 10 out of 10 standard
(9:55) Debt as an accelerant, what happens if rates rise & who else is bidding
(14:58) Inside the deal desk: what gets acquired, why they don't build & the founder question
(20:22) Building a tech giant out of Milan, Europe's talent pool & the outsider advantage
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One of the greatest viruses of the modern man is looking at Instagram Stories. You will melt your brain looking at a barrage of outcomes—like vacations, parties, cars—with no visibility of the process that got them there.
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Love is exceptionally rare. If you find it, don't let go.
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Italia no estaba en el mapa de tech, era incapaz de innovar. Ahora tampoco innova pero tiene una empresa que vale más de 20 mil millones que se llama Bending Spoons que se dedica a comprar empresas de internet mal gestionadas de Estados Unidos y las mejoran en Italia. Esto también es un mérito. Aquí el anuncio de que compran Airtable.
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Always be closing, even when you run a $200b company.
Mad respect to Ana!
One of funnier moments from Speed's World Cup run.
Two people ask for a selfie at Spain vs. France. He thinks randos. It's Ana Botín (Exec Chair of Banco Santander) and Juan Rigo (head of Mercadona, Spain's largest grocery chain).
Botín says "he's the Walmart of Spain and I'm the JPMorgan of Europe."
She pitches him to open a checking account at her US brand OpenBank with a juicy 4% deposit interest ("OpenBank like OpenAI").
Two billionaires and some of the "most important people in Europe" but Speed "has more followers" lol
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Yes, Mexico can have massive exits. Yes, fintech is still the king.
Equifax's US$750 million acquisition of Círculo de Crédito is a great first step in creating a liquidity path for the startup ecosystem.
First, this is the best strategic exit in Mexican “fintech” history. we’re talking 11.7x forward adjusted EBITDA of US$62 million, on revenue of US$134 million in the last 12 months.
That confirms the fintech infrastructure play has real exit potential in Mexico and the wider region. It is good news for the alternative-data, open-finance, behavioral-scoring, and fraud-detection startups building here, along with their investors.
Second, global incumbents no longer treat Mexico as a place for cheap acquisitions but as a new lever of growth.
In the words of Equifax CEO Mark Begor: “Mexico is one of the fastest-growing credit markets globally, expecting to grow very strong double digits over the next few years with continued strong growth thereafter.”
Third, some of the money should flow back into the startup ecosystem.
Even if there is no evidence of any VCs owning an equity stake in Círculo de Crédito, the consortium of banks, and private investors who founded it will most likely become ,or double down as, LPs into local VC funds.
Each exit like this sets a comparable for the next deal, gives investors a reason to keep writing checks, and unlocks capital that funds the next generation of founders.
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I’m so excited to share this update on @Conception –
We’ve generated the first early human eggs derived from stem cells.
This is a big deal -- the potential to redefine fertility is real.
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“He's now teaching his three kids, including his 16-year-old daughter, how to invest based on what he learned owning SpaceX stock. His daughter is already a stakeholder in Meta and a handful of other companies.
If given the chance to talk to Musk, Hernandez said he'd thank him for helping him realize a dream he didn't know he had.
‘He made it a possibility for somebody like us, you know, the cook or … electrician. He's making all these lives much better and meaningful for their families as well."
Before Juan Hernandez became a welder at SpaceX, he had never heard of the company.
But just over 10 years later, that leap of faith is paying off following the company's $75 billion initial public offering. cbsn.ws/445TrCm
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Gwynne Shotwell has got to be the most impressive woman of our generation. Mad respect.
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Juan Hernandez has about $880,000 in SpaceX stock. He picked up a welding job there in 2015 for $28 an hour, back when he had no idea what the company even built. This week, it goes public.
He wasn't chasing rockets. He'd come over from Mexico, learned to weld because it paid, and just needed steady work. A friend told him about a job. "I didn't even know what SpaceX was when my friend was talking about it," he told the Wall Street Journal. "But the money was sufficient at the time."
So he showed up and welded. SpaceX brought him on full time and handed him $10,000 in shares, the kind you have to stick around a few years to fully keep. He started putting a little of each paycheck toward more of them, year after year, while he built rockets.
By 2020 the company was worth $36 billion. Hernandez sold a bit of his stock here and there, bought some property around Texas, and set up a small real-estate business with his wife. The rest he just held.
This week SpaceX sells stock to the public for the first time, the biggest sale of its kind anyone has ever pulled off. Thousands of current and former workers own a piece of it, and the money reaches far past the engineers. It goes to the welders and technicians who build the rockets, and to the sailors who head out to scoop fallen rocket parts out of the ocean. Even the people pouring coffee at the offices got shares. Some were handed stock worth less than $2 a share, back when SpaceX had never landed a rocket and plenty of people figured it never would.
One of them is an engineer who left ten years ago. He just bought a hotel in northern Italy and is fixing it up with his shares. He's 63, and he told the Journal he doesn't want to just die with a pile of money in the bank. Other workers spent theirs on a partner's student loans, a summer house for their parents, fertility treatments, or seed money to start something of their own.
Hernandez is 42 now. He left SpaceX last year and welds at a Blue Origin launch site. "It's put me in a comfortable position for life," he said, about a job he only took because, at the time, the money was good enough.
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hiring is the highest variance decision in an early startup. one bad hire at n=4 isn’t just a 25% drag, it resets what normal looks like for the whole team. this is esp true if that not great fit person is “senior”. they bring down the entire culture.
one great hire does the opposite, & recruits the next five. the asymmetry is huge.
take this lesson to heart from my failures lol.
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We didn’t have “HR” when building Palantir, for similar reasons - I avoided Ryan’s mistake.
And when we needed some PeopleOps, we hired technical leaders.
Going into the vast majority of companies and firing most of their HR and Marketing departments would tend to create value!
This quoted post is unavailable.
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We now have a female Bryan Johnson.
It’s Kate Tolo.
She will become the most measured female in history.
+$2 million of spend per year
+ Developing a female-specific protocol
+ Sharing everything for free
To start, she will spend 3 months mapping her baseline. Men, in contrast, can get their baseline done in 1 or 2 weeks.
+ 3 months for baseline measurement
+ across 4 time points per cycle
+ doing the same thing every day
+ a dedicated full-time medical team
For context on the extensiveness of measurement, during the past 5 years, we’ve collected 1.5 billion data points on my body. I suspect Kate will exceed that given technology has improved since I started.
The goal is to create a repeatable waveform of hundreds of life-critical biomarkers. Once the baseline is acquired, she will begin interventions.
We will try to answer practically useful questions and share all of the data + learnings for free.
Can fertility be improved?
+ Should women cold plunge?
+ Can PMS symptoms be alleviated?
+ What should a female sauna protocol be?
+ Should dosage change throughout the month?
+ What keeps a cycle regular?
+ Does the body need more iron, magnesium, or protein at specific phases?
+ Should women fast?
+ Should recovery protocol change by phase?
+ What's the earliest detectable signal of perimenopause?
+ Can perimenopause be slowed?
+ How is cognitive load & mood affected?
+ Does stress impact men and women the same?
Kate has suspected endometriosis. 10% of all women do. We will try to tackle this too. I am excited for all of the surprising things we will hopefully uncover.
Unlike me, Kate does not have the innate desire to wake up at 4:30am and do six hours of longevity therapies.
She’s the cofounder of Blueprint, building in the trenches with me since day one. She understands the game and how hard it is.
In many ways, this is a sacrifice for her. She is a creative person, going from a life of freedom and spontaneity to a rigid protocol.
Traditionally, RCTs have been viewed as the gold standard. But RCTs have underserved women. The FDA banned women from clinical trials for 16 years (1977 to 1993), and most "medicine for women" is still medicine tested in men. Demanding RCT-only evidence for women's health is demanding evidence that doesn't exist. There is not enough practical scientific literature for women to reference only RCTs. It leaves half the population without a path to know what to do.
N=1 medicine is gaining ground and picking up where RCTs specifically fail. Individual science experiments give us signals that answer what to do on a day-to-day basis. This is even more important for women.
If you’re new to Kate and my world, I want you to understand that we have your back. Our intentions are to be a sturdy, reliable force in your life. To care for your best interest as we’d care for our own. We want what’s best for you and our loyalty is to your existence.
It’s pretty cool to be living in a time when we may be the first generation to not die. I’m not suggesting immortality, but lifespans so long that we stop thinking about lifespans.
At the end of the day, the one thing we each care about more than anything else is one more breath. I’m proud of Kate for taking on this responsibility. It’s painful, exhausting and costly.
The beginning of the world’s first n=2.
