Investing, for people who read the docs.

• Finance

  Why Your Backtest Is Lying to You: Data Biases That Ruin Equity Research

  Survivorship bias, look-ahead bias, point-in-time data, and the rest of the subtle ways your beautiful backtest is overstating returns. With concrete fixes for each.

  2026-05-19 · 5 min read

• Finance

  The Boring Math of Compound Returns (And Why Everyone Gets It Wrong)

  Compound interest sounds like magic. The math is mundane and the most common rules of thumb are subtly wrong. Here's a calmer take on what compounding actually delivers.

  2026-05-19 · 5 min read

• Finance

  Index Funds, ETFs, Mutual Funds: What Actually Differs (and When It Matters)

  The three labels overlap more than the marketing suggests. A developer-friendly breakdown of structure, tax treatment, and the cases where the difference actually changes your decision.

  2026-05-19 · 5 min read

• Finance

  Polygon vs Alpha Vantage: Which Stock Data API Fits a Side-Project Budget

  Polygon and Alpha Vantage are the two common entry points for developer-side stock data. A side-by-side on free tiers, coverage, and developer experience — without the trading-edge hype.

  2026-05-19 · 6 min read

• Finance

  SEC EDGAR for Developers: The Free Fundamentals API Hiding in Plain Sight

  Most stock-data tutorials skip past the one free, public, no-rate-limit source for US company filings. Here's how to read fundamentals straight from SEC EDGAR, JSON-first.

  2026-05-19 · 5 min read

• Finance

  What Diversification Actually Buys You (and What It Doesn't)

  Diversification reduces idiosyncratic risk, not market risk. When the distinction matters, what correlation looks like under stress, and why 60/40 isn't a free lunch.

  2026-05-19 · 5 min read

• Finance

  What 'Rules-Based Investing' Actually Means (And What It Doesn't)

  Rules-based investing isn't AI, isn't HFT, and isn't a guarantee. It's a behavioral discipline: decide the action before the event. Here's what counts as a rule, what doesn't, and how it actually fails.

  2026-05-19 · 5 min read

• Finance

  Why we're writing about investing on a developer tools blog

  Tools, evidence, and disclosure are the same job whether the topic is a code editor or a brokerage account. Here's the editorial line for the new finance section.

  2026-05-19 · 1 min read

What you won't find here

• No stock picks

  No buy/sell calls, no target prices, no "this is the one" essays.

• No guaranteed returns

  Past performance isn't predictive. We say so out loud.

• No tax or legal advice

  Rules vary by jurisdiction. Ask a CPA, not a blog.