Most risk-of-ruin Monte Carlo resamples a strategy's realised P&L, which quietly bakes in the good luck you are trying to stress and understates the tail. Here is the correction that made my honest drawdown distribution far fatter than my first one, plus the relative gate a long-only sleeve actually needs. First person, British English, illustrative numbers only.
Look-ahead bias is the default state of careless backtest code, not an exotic edge case, and it survives review because it reads as ordinary pandas. Here is the corrupt-the-future causality test I now gate on: poison every price after a date, then assert nothing computed before it moves. If the past shifts when you poison the future, the strategy is reading ahead.
A series mining the PhD thesis on London and UK office buildings (Azhari, 2025). Key takeaway. Greater London holds 30 per cent of office floor area and 24 per cent of office premises in England and Wales, which makes it a clean proxy for some questions, a misleading one for others, and a context-dependent proxy for many.
One argument recurs constantly in Syrian conversation today, and it is true in much of what it claims: "there are problems, but things are better than they were under Assad". The problem begins the moment it stops describing reality and starts answering every question. This piece separates the question of how far we have come from the question of where we are going, distinguishes rights that need capacity from rights that need only a decision, and sets out a floor of demands that needs no budget and no ten years.
The expected best Sharpe of a parameter sweep climbs as the grid grows, even when every strategy in it is worthless. Here is the deflated Sharpe ratio explained as a practitioner sees it, with a small N to noise-ceiling lookup table you can apply to your own sweep tonight, and the one rule that killed my proudest grid-search winner: N is the pool, not the podium.
A series mining the PhD thesis London and UK Office Buildings (Azhari, 2025). Key takeaway. The UK mainstream office benchmarks ECG-19 and CIBSE TM46 rest on a 1992 study, and the Greater London data shows actual offices nowhere near those values, so a refresh is overdue.
The most dangerous code in a trading repo is the throwaway research notebook. One structural rule, dependencies that flow in a single direction, keeps it out of production and turns invisible coupling into a number you can grep.