A backtest can make almost any strategy look brilliant. Tweak enough settings, ignore a few costs, pick the right dates, and you'll have a beautiful equity curve that falls apart the moment you trade it live.

Here are the most common backtesting mistakes options traders make, and how to avoid each one so your results are something you can actually trust.

1. Ignoring trading costs

Brokerage, taxes, exchange charges and slippage add up fast, especially for strategies that trade every day with several legs. A strategy that makes a small profit per trade can be negative after costs.

Fix: Always include slippage, brokerage and other costs. On the OPIFY backtester, set slippage in points, brokerage per trade cycle, and other costs as a percentage.

2. Overfitting

Overfitting means tuning your settings so precisely to past data that they capture random noise rather than a real edge. Signs include:

• Odd, precise values, like a stop-loss of 23.7% or entry at 9:37.
• Results that fall apart when you change a setting slightly.
• Many rules added to remove specific losing trades.

Fix: Use round, sensible values. Check that nearby values also work. If 20%, 25% and 30% stop-losses all perform reasonably, that's a sign of robustness.

3. Testing too short a period

Three months of data might cover only one type of market. A strategy that shines in a calm, range-bound period can be destroyed by a volatile one.

Fix: Test over a year or more where possible. NIFTY and BANKNIFTY data on OPIFY goes back to January 2023, and SENSEX to May 2024.

4. Testing only one period

Even a long test can hide the fact that all the profit came from one good stretch.

Fix: Use Performance Comparison to compare two timeframes, and check the calendar view for months with large losses.

5. Looking only at net profit

Net profit hides drawdowns, losing streaks and the worst trade.

Fix: Always check max drawdown, profit factor, expectancy, worst trade and losing streak together.

6. Not checking the trade log

Sometimes rules don't do what you think. A stop-loss set on the wrong basis, a leg on the wrong strike, an exit at the wrong time.

Fix: Open the Trade Logs and check several trades by hand, especially the biggest wins and losses.

7. Ignoring position size and capital

A strategy's ₹ results mean little without the capital it needs. Option selling strategies can block large margin.

Fix: Set initial capital (or let it be calculated from margin) and look at ROI and drawdown as a % of capital.

8. Assuming live results will match

Live trading adds real slippage, missed entries, emotions and market conditions the past didn't have.

Fix: After a good backtest, practise the strategy in the options simulator, then start live with small size.

A trustworthy backtest checklist

Frequently asked questions

How many trades make a backtest reliable?

More is better. Many traders want at least 100 trades before trusting the statistics.

Is a backtest useless then?

Not at all. A careful backtest is the best way to reject bad ideas cheaply and to understand the risk of good ones.

This article is for education only and is not investment advice. Past performance does not guarantee future results.