Why pitfalls happen
Backtests feel objective because they produce numbers and charts. But most backtest mistakes come from:- wrong assumptions (timeframe, execution, intrabar behavior)
- overfitting (optimizing to the past)
- ignoring risk (drawdown, tail losses)
- ignoring data limitations (coverage, gaps, warmup)
Pitfall 1: Starting with total return
If you start with the biggest number (PnL / CAGR), you will:- overfit quickly
- ignore risk
- misunderstand behavior
- read results in the correct order
How to read results
Use a stable workflow for every backtest.
Pitfall 2: Ignoring trade count
A strategy with 7 trades can look incredible by chance. Fix:- require a meaningful trade sample
- validate behavior across multiple ranges
Low trade count = high uncertainty.
Pitfall 3: Expecting intrabar triggers
Many traders expect:- entries on candle highs/lows
- instant crossovers mid-candle
- design strategies for candle-close evaluation
- validate triggers using trade history
Pitfall 4: Confusing events and states
Common mistake:- using a crossover (event) as if it were a persistent condition (state)
- “EMA crosses above EMA” triggers once
- “EMA is above EMA” stays true
- use events for triggers
- use states for filters
Crossovers & trend changes
Events vs states explained clearly.
Pitfall 5: Over-filtering the strategy
Too many filters often lead to:- almost no trades
- misleading metrics
- “perfect” equity curves that are just inactivity
- start with a baseline strategy
- add one filter at a time
Pitfall 6: Exit logic dominates (but you don’t notice)
A strategy can appear profitable because:- TP/SL choices dominate outcomes
- exits are too wide/tight
- one extreme trade drives results
- simplify exits
- inspect the biggest wins/losses
- validate distribution, not just averages
Pitfall 7: Over-optimizing parameters
Tuning parameters to maximize past performance often creates:- fragile strategies
- collapse out of sample
- regime dependence
- small parameter changes should not destroy performance
- test across multiple time ranges
- prefer robust parameter zones
Indicator parameters
Understand how parameters change behavior.
Pitfall 8: Ignoring data coverage and warmup
Common symptoms:- “strategy doesn’t trade early in the backtest”
- “results look broken in old periods”
- “backtest range got adjusted”
- confirm data coverage
- understand indicator warmup behavior
Data coverage
Learn how coverage affects results.
Pitfall 9: Assuming one market equals all markets
A strategy that works on BTC may fail on:- ETH
- altcoins
- other volatility regimes
- test on multiple markets
- look for behavior consistency, not peak returns
Pitfall 10: Ignoring drawdown duration
Many traders only look at max drawdown, not how long it lasts. A strategy can have:- acceptable max drawdown
- but extremely long recovery periods
- evaluate drawdown duration alongside max drawdown
Quick self-check
Before trusting a backtest, ask:- Do I understand the first 10 trades?
- Do I have enough trades for confidence?
- Is risk acceptable (DD + duration + tail trades)?
- Does it work across multiple ranges?
- Does it survive small parameter/timeframe changes?
What to read next
How to read results
A step-by-step workflow.
Metrics explained
Interpret numbers correctly.
Trade history & logs
Debug trade-by-trade.
Improving a strategy
Iterate without overfitting.
The easiest backtests to believe are often the most dangerous.