Fail Closed Data Validation: Why a Trading Bot Should Refuse to Boot on Bad Data

A data-quality gate that crash-loops on corrupt, stale or all-NaN data is not broken, it is working: the alternative is fail open, trading on garbage with silent defaults. Here is the war-story from both sides, the honest flip where an over-eager gate locked me out of a market, and the one portable rule: on bad data, refuse to trade and alert loudly, never proceed with a default that looks like data.

By Rayan Azhari · 9 min read · Essays

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Adjusted vs Unadjusted Close: The Dividend Double-Count That Fakes a Backtest Edge

Total-return and price-return series look identical on a chart and differ by percent-per-year underneath. Mix them, or fold dividends in twice, and a long-horizon backtest drifts a few percent above the honest one every year and compounds into a phantom edge. Here is the reconstruction check I now run: rebuild total return from price plus the dividend stream yourself and diff it against the vendor's adjusted series.

2026-10-02 · 9 min

Survivorship Bias in a Backtest: The Delisted-Fraction Smell Test

Survivorship bias is the term every quant knows and almost nobody makes actionable. Here is the one-number diagnostic I run before I trust any cross-sectional backtest: count the dead names as a share of your universe over a decade. If it is near zero, your data quietly deleted the losers and every result is biased upward.

2026-09-25 · 9 min

Capacity and Crowding: Why a Real Edge Still Decays at Size

Even a genuine edge dies if you deploy it too large. This is the field note on alpha-side risk: how your own market impact (capacity) and everyone else trading the same signal (crowding) shrink the size at which the edge is still yours, and the crossover test that tells you where your ceiling sits before the market finds it for you.

2026-09-18 · 9 min

Before the Register Is Digitised: What Syria's Property Conference Did Not Say

On 15 September 2026 the Ministry of Local Administration held a conference on real estate management and property rights and proposed four things: digitise the land registers, simplify procedures, steer development by property data, and find financing. None of the four decides whose name belongs in the register. That is settled by at least nine statutes, most written by the government this one replaced and every one still in force, and the conference named none of them. This piece sets the instruments out with their windows and remedies, reads the register's own coverage figures, follows one family through Law 33's six months, and puts five other states' claims mechanisms beside Syria's, on each body's own numbers.

2026-09-15

Article 15: What Is a Building? How the UK Counts Its Stock

A series mining the PhD thesis on London and UK office buildings (Azhari, 2025). Key takeaway. There is no single answer to what is a building in UK data: four agencies keep four definitions, and stock-level energy work has to build a synthesis, the Self-Contained Unit.

2026-09-15 · 14 min

Diesel at 175: What Syria's Fuel Price Rise Shows, and What It Does Not

On 13 September 2026 diesel in Syria went from 125 to 175 new pounds a litre, and by Sunday afternoon roads were closed in four governorates. This piece sets out what the record establishes about that price and what it does not: a pricing committee with a list of factors and no formula, a world price the ministry cited but did not show, a stated need of 300,000 barrels a day of which a fifth is itemised, two import shares from one ministry on one day, and a population with nothing between it and the price. Five charts, every figure with its publisher, unit and date.

2026-09-14

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