About Long-Term Investing Guide
Long-Term Investing Guide is an independent educational website. It pairs a browser-based historical investment simulator with plain-English explanations of risk, valuation, diversification, and time horizon. The site is designed for retail investors who want to test ideas against real historical price data before committing capital.
Our mission
Make investment decision-making more disciplined. We prioritize clarity over hype and encourage readers to evaluate downside risk, time horizon, and personal constraints before allocating capital. Every claim on the site is either derived from the public price data files we ship with the simulator, or from documented assumptions stated in plain text.
How the simulator is built (Experience signal)
The simulator is a Web Component written in vanilla JavaScript. It loads monthly closing-price CSVs maintained inside this repository, runs a deterministic month-by-month allocation over the user's selected period, and renders the result with Chart.js. Because the entire calculation runs client-side, you can read the source code or download the CSV files and reproduce every number we report.
- Data span: US tickers and S&P 500 from 2010 to the most recent monthly close.
- Korean market: KOSPI, Samsung Electronics, SK Hynix, and Hanwha Aerospace from 2010.
- Update cadence: Monthly close prices appended after each month ends; news headlines refresh daily.
- Reproducibility: CSVs are versioned in git; script tags use `?v=` cache busters whenever the simulator logic changes.
Editor and author
Sun Park is the editor and maintainer of Long-Term Investing Guide. Sun built the simulator from scratch as a way to answer one repeated question from friends and family: "what would have happened if I had invested X every month into Y for Z years?" The site grew from that single tool into a structured library of explanatory articles intended to help readers interpret simulator outputs responsibly.
Sun is not a licensed investment adviser, broker, or fund manager. The site does not offer personalized advice. The author's role is editorial: writing, sourcing data, and maintaining the simulator's accuracy.
Reach the editor by email through the contact page. Source code and data files are public on GitHub.
What this site is not
We do not provide personalized financial advice, brokerage services, portfolio management, or guaranteed return claims. The simulator does not model taxes, dividends, trading fees, slippage, bid/ask spreads, or account-specific rules. Real-world results will differ.
How to verify our work
- Reproduce a simulation: Open the homepage, pick the same asset and date range used in any article, and confirm the totals match.
- Inspect the data: All CSVs are at the site root and inside the `data/` folder. Each row is one month's closing price.
- Read the source: The simulator file is `stock-calculator.js`; the data loader is `market-data.js`. Both are unminified.
- Report a discrepancy: Use the contact page with the URL, the parameters, and the source you used to cross-check.
Editorial governance
Editorial standards (originality, accuracy, corrections, commercial transparency, content safety) are documented on the editorial policy page. Privacy practices are documented in our privacy policy.