Articles
Plain-English guides to how strategy testing actually works, and where it quietly misleads you.
All of it is educational background for the builder and the screeners. None of it is investment advice.
AI concentration risk in index funds
Ten stocks are now roughly 38% of the S&P 500, most of them tied to the same AI story. What that means for a fund sold to you as diversified, what happened in four historical concentrated markets — the Nifty Fifty, Japan, dot-com, and the times the skeptics were early and wrong — and the mechanics passive investors use to measure and manage the exposure, with the real cost of each.
How backtesting actually works
The backtest loop step by step, from defining a universe to compounding an equity curve. What each output metric answers and what it hides, the six ways a backtest misleads you, the difference between in-sample and out-of-sample, and a checklist for reading anyone else's impressive results — including the ones on this site.
Survivorship bias, explained
Why testing on the companies that still exist today silently deletes every failure, starting with the WWII bomber-armor problem that made the idea famous. Where the bias hides in market data, how large the distortion gets, the related delisting and reconstitution biases, and how to avoid it — plus an honest account of how it affects StratPick's own numbers.
Investor profiles
How five very different people actually invested, what the record really shows, and the honest limits of copying any of them.
Warren Buffett
Quality businesses at sensible prices, held for decades. The Berkshire record verified, the evolution from Graham's cigar butts to Munger's quality, and the parts of his edge — insurance float, crisis-era deals, sheer size — that nobody else can copy.
Peter Lynch
Growth at a reasonable price, and the 29.2% annual return that made Magellan the largest fund in the world. His six categories of stock, the PEG ratio, and why the average investor in his fund did far worse than the fund did.
Benjamin Graham
The man who turned investing into arithmetic. Margin of safety, Mr. Market, and net-nets — plus why his own returns are genuinely disputed, and why his most successful student deliberately moved on from his method.
John Bogle
The argument that trying to win is how most investors lose. Vanguard, “Bogle's Folly,” the cost-matters hypothesis, and the criticisms of indexing — including the concentration problem — that he never fully answered.
Jim Simons
The mathematician behind the best record ever documented: roughly 66% a year gross for three decades. What quantitative investing actually is, and why Medallion is the least replicable success in finance.
Elsewhere on the site
- Scoring methodology — how the leaderboard ranks strategies, and its limitations
- About StratPick — what this is, who built it, and the data caveats