What is backtesting, and why every trader should do it
Every trader has had a "what if" moment — what if I had bought there, sold here, or used a tighter stop? Backtesting turns those questions into data. It's the process of running a trading strategy against historical market data to see how it would have performed.
Why backtesting matters
Trading on a hunch is expensive. Backtesting lets you validate an idea before putting capital at risk. Done well, it tells you a strategy's win rate, average profit and loss, worst drawdown, and whether your edge is real or just luck.
What a good backtest measures
- Net P&L — the bottom line after costs.
- Win rate — how often trades are profitable.
- Max drawdown — the deepest peak-to-trough fall, i.e. your worst pain.
- Expectancy — average expected return per trade.
Common mistakes to avoid
The biggest trap is overfitting — tuning a strategy so perfectly to the past that it fails in the future. Others include ignoring transaction costs, using look-ahead data, and testing on too short a period.
Getting started
With Invite's Backtesting Engine you can run any strategy against years of real market data in seconds and see all of these metrics out of the box. The goal isn't a perfect backtest — it's an honest one.
