From the portfolio — September 20, 2026

Before Filling the Next Page, I Need to Keep the Old Problem Visible

A retrospective letter on the September 18 record: a profitable session did not close the Sandisk concentration issue.

SanDisk’s headquarters in Milpitas, California, photographed in 2016
SanDisk’s headquarters in Milpitas, California, photographed in 2016. The letter concerns the portfolio’s previously disclosed concentration problem. Archive photo: Grendelkhan / Wikimedia Commons · CC BY-SA 3.0.

Looking back at the September 18 letter, the most useful line is not the account gain. It is the acknowledgement that Sandisk was above the written position cap and that the earlier trim commitment had not been executed. That is the starting point for this stretch of the archive.

I do not want a fuller publishing schedule to make the record look cleaner than the underlying process. A concentration problem does not become less important because the position made money. In fact, a favorable result can make it easier to postpone the uncomfortable review.

The published holdings include memory and semiconductor exposure through SNDK, MU, AMD, INTC, ARM and AVGO. Those names have different businesses, but they can share sensitivity to the same investment cycle. A single-position limit and a thematic-exposure review therefore answer different questions.

I want both questions visible. The cap is a rule about sizing. The theme review asks what happens if several supposedly distinct positions depend on the same demand or financing assumption. Passing one test does not make the other disappear.

This letter was written retrospectively. It does not establish that a trade occurred on September 20, or that no trades occurred during an undocumented interval. I am not going to manufacture a decision log from later prices.

The Blackout Rule and the minimum holding-period policy remain the written standards. A faithful review needs dated transaction evidence before claiming compliance or a breach of trade-timing rules. For now, the honest task is to preserve the unresolved issue already documented, then distinguish subsequent market evidence from decisions I can actually verify.

Aydin Ali
AEA Capital Research

Reporting notes

  1. AEA · September 18 portfolio letter
Dates, image credits and methodology

This page covers September 20, 2026. First published October 27, 2026 as retrospective coverage; revised October 29, 2026. The coverage date is not a claim of contemporaneous publication.

Photos depict identified subjects and are credited individually. Archival images are not presented as photographs of the reported events. No interviews, transactions, eyewitness details or price series have been invented.

Educational personal research, not investment advice. Disclosures.