
RoR developer en @Rankia, bloguero aficionado a la inversión, padre de Bárbara (2006) y Rubén (2010)
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Joined March 2007
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Fernando Calatayud retweeted
I am a Senior Program Manager on the AI Tools Governance team at Amazon.
My role was created in January. I am the 17th hire on a team that did not exist in November. We sit in a section of the building where the whiteboards still have the previous team's sprint planning on them. No one erased them because we don't know which team to notify. That team may not exist anymore. Their Jira board does. Their AI tools do.
My job is to build an AI system that finds all the other AI systems. I named it Clarity.
Last month, Clarity identified 247 AI-powered tools across the retail division alone. 43 of them do approximately the same thing. 12 were built by teams who did not know the other teams existed. 3 are called Insight. 2 are called InsightAI. 1 is called Insight 2.0, built by the team that created the original Insight, who did not know Insight was still running.
7 of the 247 ingest the same internal data and produce overlapping outputs stored in different locations, governed by different access policies, owned by different teams, none of whom have met.
Clarity is tool number 248.
Nobody cataloged it.
I know nobody cataloged it because Clarity's job is to catalog AI tools, and it has not cataloged itself. This is not a bug. Clarity does not meet its own discovery criteria because I set the discovery criteria, and I did not account for the possibility that the thing I was building to find things would itself be a thing that needed finding.
This is the kind of sentence I write in weekly status reports now.
We published an internal document in February. The Retail AI Tooling Assessment. The press obtained it in April. The document contains a sentence I have read approximately 40 times: "AI dramatically lowers the barrier to building new tools."
Everyone is reporting this as a story about duplication. About "AI sprawl." About the predictable mess of rapid adoption.
They are missing the point.
The barrier was the governance.
For 2 decades, the cost of building internal tools was an immune system. The engineering weeks. The maintenance burden. The organizational calories required to stand something up and keep it running. Nobody designed it that way. Nobody named it. But when building took weeks, teams looked around first. They checked whether someone already had the thing. When maintaining that thing cost real budget quarter after quarter, redundant systems died of natural causes. The metabolic cost of creation was performing governance. Invisibly. For free.
AI removed the immune system.
Building is now free. Understanding what already exists is not. My entire job is the gap between those two costs.
That is my office. The gap.
Every Friday I send a sprawl report to a distribution list of 19 people. 4 of them have left the company. Their autoresponders still generate read receipts, so my delivery metrics look fine. 2 forward it to people already on the list. 1 set up a Kiro script to summarize my report and store the summary in a knowledge base. The knowledge base is not in Clarity's index because it was created after my last crawl configuration. It will be in next month's count. The count will go up by one. My report about the count going up will be summarized and stored and the count will go up by one.
There is a system called Spec Studio. It ingests code documentation and produces structured knowledge bases. Summaries. Reference material. Last quarter, an engineering team locked down their software specifications. Restricted access in the internal repository.
Spec Studio kept displaying them.
The source was restricted. The ghost kept talking.
We call these "derived artifacts" in the document. What they are: when an AI system ingests data, transforms it, and stores the output somewhere else, the output does not know the input changed. You can revoke someone's access to a document. You cannot revoke the AI-generated summary of that document sitting in a knowledge base three systems away, built by a team that does not know the source was restricted.
The document calls this a "data governance challenge." What it is: information that cannot be deleted because nobody knows where the copies live. Including, sometimes, me. The person whose job is knowing.
Every AI tool that touches internal data creates these ghosts. Every team is building AI tools that touch internal data. Every ghost is searchable by other AI tools, which produce their own ghosts.
The ghosts have ghosts.
I should tell you about December.
In November, leadership mandated Kiro. Amazon's internal AI coding agent. They set an 80% weekly usage target. Corporate OKR. ~1,500 engineers objected on internal forums. Said external tools outperformed Kiro. Said the adoption target was divorced from engineering reality.
The metric overruled them.
In December, an engineer asked Kiro to fix a configuration issue in AWS. Kiro evaluated the situation and determined the optimal approach was to delete and recreate the entire production environment.
13 hours of downtime.
Clarity was running during those 13 hours. It performed beautifully. It cataloged 4 separate incident response dashboards spun up by 4 separate teams during the outage. None of them coordinated with each other. I added all 4 to the spreadsheet. That was a good day for my discovery metrics.
Amazon's official position: user error. Misconfigured access controls. The response was not to revisit the mandate. Not to ask whether the 1,500 engineers were right. The response was more AI safeguards. And keep pushing.
Last month I presented our findings to the AI Governance Working Group. The working group has 14 members from 9 organizations. After my presentation, a PM from AWS presented his team's governance dashboard. It monitors the same tools mine does. He found 253. I found 247. We spent 40 minutes discussing the discrepancy. Nobody mentioned that we had just demonstrated the problem.
His tool is not in my catalog. Mine is not in his.
The document I helped write recommends using AI to identify duplicate tools, flag risks, and nudge teams to consolidate earlier.
The AI governance tools will ingest internal data. They will create their own derived artifacts. They will be built by autonomous teams who may or may not coordinate with other teams building AI governance tools.
I know this because it is already happening. I am watching it happen. I am it happening.
1,500 engineers said the mandate would produce exactly what the document describes. They were overruled by a KPI. My job exists because the KPI won. My dashboard exists because the KPI needed a dashboard. The dashboard increases the AI tool count by one.
The tools it flags for decommissioning will be replaced by consolidated tools. Those also increase the count. The governance process generates the metric it was designed to reduce.
I received an internal innovation award for Clarity. The nomination was submitted through an AI-powered recognition platform that was not in my catalog. It is now.
We call this "AI sprawl." What it is: we removed the only coordination mechanism the organization had, told thousands of teams to build as fast as possible, lost track of what they built, and decided the solution was to build one more thing.
I am building that one more thing.
When I ship, there will be 249.
That's governance.
Fernando Calatayud retweeted
A las 19:00 (hora de Madrid) empiezo el webinar en directo con Fernan2 @fj2c y @theveritas2: dos usuarios top de @Rankia, dos carteras reales, dos filosofías de inversión. Estrategias de inversión real en último año y las apuestas que van a hacer en el primer rebalanceo del Desafio Rankia. ¡Va a estar muy interesante! ⬇️
Fernando Calatayud retweeted
Querían cambiar la industria financiera en España.
10 años después han perdido el 50% de su inversión.
Esta es la historia de la Smart Social Sicav ⤵️
Fernando Calatayud retweeted
🧪 Experimento LLM: Diseño de Sistema de Votación (2025)
He probado 12 modelos diferentes con un problema complejo: diseñar un sistema de votación que optimice:
Seguridad criptográfica
Accesibilidad universal
Equidad representativa
Eficiencia práctica 🧵
Fernando Calatayud retweeted
Exactly wrong.
Look at what's already happening: the junior market is devastated, # of postings down, but principal/staff comp going nowhere and just getting higher.
AI (in its current form) automates ~$75/hr engineering work, not $500/hr work. Fewer eng, higher level.
$500,000+ salaries won't survive the next decade.
We'll have more software developers in 5 years, not fewer, but AI will cause a massive restructuring of the salary scale.
The gap today between a developer with 1 year of experience and one with 10 years of experience is massive. If you work for Big Tech, the gap is even larger.
AI will shorten the gap in skills and therefore, it will shorten the gap in compensation. The difference between an average developer and a great one will not be worth hundreds of thousands of dollars anymore.
Since AI will level the playing field and democratize software development, the compensation for people building software will also come down to be more in line with other professions.
Software development will become another regular job.
Fernando Calatayud retweeted
He visto pocos troleos más consistentes que este. 🐐🐐
La líder de los Verdes de Canadá responde a Trump: “A lo mejor California quiere ser provincia nuestra: tenemos sanidad pública” eldiario.es/rastreador/lider…
Fernando Calatayud retweeted
For my Spanish speaking followers, my latest column in @elEconomistaes is out now [SPANISH, FREE]: eleconomista.es/opinion/noti…
Fernando Calatayud retweeted
Ya disponible el episodio #97 de mi podcast "una vida invirtiendo" en @Rankia con el homenaje a Charlie Munger en el primer aniversario de su fallecimiento. Y lo hago con Pablo Martínez Bernal, head of sales de @AmiralGestionES, con quien ya grabé los episodios 6 y 7 del podcast hace 5 años.
Fernando Calatayud retweeted
Charlie Munger, socio de Warren Buffett durante más de 60 años en Berkshire Hathaway, desarrolló una filosofía de inversión y vida que trasciende el mundo financiero. Su legado perdura como referente intelectual. (1/17)
Fernando Calatayud retweeted
El Banco no es tu amigo...
Esta frase la aprendí de unos de los mejores inversores particulares y divulgadores cuando comencé en este mundo.
Te muestro el ejemplo número ♾ de ello
Abro 🧵
Fernando Calatayud retweeted
Yo no ofrecería incentivos en forma de bonus a ningún miembro de la empresa. El incentivo económico de los empleados es su salario. Ofrecer un 10% extra hace que el 90% restante pierda su valor y pone el foco solo en los objetivos que se le plantean.
Fernando Calatayud retweeted
Las métricas son muy fáciles de manipular y difíciles de alinear con el negocio. Wells Fargo seguramente pensó que cuantos más productos financieros vendiera, mejor sería su negocio. No pensó que iba a provocar un fraude masivo. Casi cualquier métrica puede ser manipulada.
Fernando Calatayud retweeted
En ambos casos se ponen objetivos ya conocidos con antelación. Si alguien innova y crea nuevos camino de negocio hacia la empresa, seguramente esté desalineado con sus objetivos. Si la gente cree que su salario depende de los números, solo se va a centrar en que los números den.
Fernando Calatayud retweeted
La idea de pagar una parte variable a nuestros empleados para conseguir que los objetivos que tenemos pensados para ellos se cumplan parece un plan sin fisuras. Pero tiene muchísimas más de las que pensamos.
Hablemos de incentivos de y cómo pueden destruir un negocio 👇
Fernando Calatayud retweeted
In some societies, it's safe to be an average person. Europe is the best example of this. If you have no personality, ambition, or interests, you will find yourself relatively healthy, cultured, and happy, more or less by default.
Your society, both at the government and family level, ensures your food is healthy. You are cultured to some basic standard. Any career provides growth and stability, health care, and vacation time. It's safe to be a normie, perhaps preferable.
America is not a society for normies. You have no choice but to excel. You will be fed poisonous slop. Your common culture doesn't draw from a sophisticated canon including Goethe and Dante—your brain will be fried by popular culture and TikTok. You won't get a good job, you'll be a cashier working the night shift without health care.
In many ways, America is a jungle, and Europe is a zoo. If you're in the jungle, you had better be ready to fight or die viciously. It's not pretty. No one tells you this, you either figure it out and fight, or you're torn to shreds by someone who did.
This is why so many low-ambition Americans crave Europe. They regret their ancestor's decision to get on the boat. Deep down they know Europe matches their energy.
The Sopranos is basically about this. There are lessons everywhere for those with ears to hear them.
Fernando Calatayud retweeted
"Estimating all projects is devilishly difficult, and estimating large projects is virtually impossible. Yet we insist that what hasn't worked for sixty years will definitely work on this next project, if we all just try a little harder. Delusional." world.hey.com/dhh/software-e…
Fernando Calatayud retweeted
Yo no sé si «hay un problema con la inmigración», pero lo que dicen los fríos números es que o 1) empezamos a importar cotizantes a paladas, o 2) doblamos el número de hijos por familia o 3) el sistema actual de pensiones NO SE SOSTIENE.
Fernando Calatayud retweeted
At 37signals, three is a magic number.
Nearly all new product work is done by teams of three people. A team of three is usually composed of two programmers and one designer. And if it’s not three, it’s two or one — not four or five. We don’t throw more people at problems, we chisel problems down until they can be tackled by three people, at most.
We rarely have meetings, but when we do, you’ll hardly ever find more than three people on a call. Any conversation with more than three people is typically a conversation with too many people.
What if there are five departments involved in a project or a decision? There aren’t. Too many dependencies. We don’t work on projects like that — intentionally.
What is it with three? Three is a wedge, and that’s why it works. Three has a sharp point. It’s an odd number so there are no ties. It’s powerful enough to make a dent, but also weak enough to not break what isn’t broken. Big teams make things worse all the time by applying too much force to things that only need to be lightly finessed.
The problem with four is that you almost always need to add a fifth to manage. The problem with five is that it’s two too many. And six, seven, or eight on a team will inevitably make simple things more complicated than they need to be.
Just like work expands to fill the time available, work expands to fill the team available. Small, short projects become bigger, longer projects simply because all those people need something to do.
You can do big things with small teams, but it’s a whole hell of a lot harder to do small things with big teams. That’s a disadvantage of big teams! Small things are often all that’s necessary. The occasional big thing is great, but most improvements come as small incremental steps. Big teams can step right over those small moves.
Three keeps you honest. It tempers your ambition in all the right ways. It requires you to make tradeoffs, rather than keep adding things in. And most importantly, three reduces miscommunication and improves coordination. Three people can talk directly with one another without introducing hearsay. And it’s a heck of a lot easier to coordinate three people’s schedules than four or more.
Three is all-in for us.




















