Portico

Notes on rational investing and the search for asymmetric opportunities.

What is Portico?

Portico is a public investment logbook — a written record of how I think, what I invest in, and why.

The name is not accidental.

The Stoics understood something that most investors learn the hard way: you cannot control markets, prices, or outcomes — only your own reasoning and decisions. Investing will test you. I am convinced that the most durable edge in investing is not informational or analytical — it is psychological. The ability to think rationally when everything around you is not.

The Stoics used to meet and reflect at the Stoa Poikile, the portico in Athens where Zeno taught philosophy around 300 BC.

Portico is a place to think clearly before acting. That is what this publication is meant to be.

Who writes it?

I’m D. Contreras. I spent 15 years in institutional equity research and portfolio management, covering hundreds of companies and raising hundreds of millions of dollars in AuM.

In February 2026, I resigned to invest my own capital independently — no mandate, no benchmark, no misaligned incentives.

Portico is the public record of that journey.

How I invest

I invest only when three conditions are met simultaneously.

First, a sensible estimate of intrinsic value with meaningful margin of safety — the upside must survive a reasonable error in my assumptions.

Second, a specific reason why the market would be wrong — not “the market is irrational,” but a named cognitive bias, forced selling, structural blind spot, or information gap that explains the mispricing.

Third, a credible catalyst — a specific, observable event that could close the gap between price and value.

When all three are present, I act decisively. When they are not, I am completely comfortable doing nothing.

Why public?

Two reasons.

The first is accountability. Writing exposes weak thinking. If you cannot explain an investment clearly on paper, you do not understand it well enough to own it. The discipline of putting ideas into words forces intellectual honesty — about what you know, what you are assuming, and what you simply do not know yet. I am convinced that publishing my investment process — including the mistakes — will make me a better investor.

The second is the pursuit of a dream. Portico is a step toward building Portico Capital Partnership — modeled on the Nomad Investment Partnership of Nick Sleep and Qais Zakaria. Their letters changed how I think about investing. Reading them was what finally convinced me to take this step. The Substack is the track record being built in public.

What you’ll find here

— Philosophy — Essays on the principles behind rational investing.

— Ideas & Deep Dives — Investment theses, from the initial idea to full valuation.

— Earnings Reviews — Updates on portfolio companies as the thesis evolves.

— Portfolio — Performance and positioning updates.

— Insights — Notes on books, podcasts, and ideas worth thinking about.

— Tools — The research infrastructure behind Portico.

Skin in the game

Every investment idea published here is one I have personally invested in or am seriously considering with my own capital. No sponsored content. No advertisements. No conflicts of interest.

Disclaimer

Nothing published on Portico constitutes investment advice or a recommendation to buy or sell any security. I am not a licensed investment advisor. Everything here reflects my personal analysis and opinions. Do your own research.

by D. Contreras