Woo Joong
What Is Overfitting in Backtesting (And How to Avoid It)
Overfitting is why a beautiful backtest and a losing strategy are so often the same thing. What it…
What Is Inflation, Really? A Plain-English Breakdown
Inflation isn’t just ‘things are expensive right now.’ What it really is, how CPI and PCE measure it,…
What Is APR vs APY? The Difference That Costs You Thousands
APR is what you pay to borrow; APY is what you earn to save — and APY includes…
What Are Fractional Shares? How to Invest When You Can’t Afford a Full Share
A fractional share lets you buy part of a share by the dollar — so $10 buys into…
Walk-Forward Analysis: Testing a Strategy Like a Quant
Walk-forward analysis re-optimizes on a rolling window and tests once on the next unseen slice. How it works,…
VTI vs VOO: Which Benchmark ETF Should You Hold for Life?
VTI vs VOO: same issuer, same 0.03% fee, about 82% of the same holdings. The one real difference…
The Difference Between Trading and Investing (And Why It Matters)
Trading and investing look alike from outside but are different activities. How they differ in horizon, tax treatment…
Total Market vs S&P 500 Index Funds: Does the Difference Matter?
A total-market fund holds ~3,600 US stocks; an S&P 500 fund holds ~500. The one real structural difference…
The Yield Curve Inversion, Explained Without the Jargon
An inverted yield curve is the recession signal everyone quotes and few explain. What the curve is, why…
Target-Date Funds Explained: Set-and-Forget Investing, Reviewed
A target-date fund is a whole portfolio in one ticker that reshapes itself as you age. How the…