S&P 500 Intraday Strategy Backtest (12-Month Results Explained)

Backtesting is one of the most useful ways to understand how a trading strategy would have behaved under past market conditions.

For a simple intraday strategy, backtesting can help answer a basic but important question: how sensitive are the results to the stop loss and take profit settings being used?

This page explains how the Twintraday strategy is tested over a rolling 12-month period, what the backtest is designed to measure, and what the results suggest about using a structured buy-and-sell intraday approach on the S&P 500.

What is being tested

The Twintraday concept is based on opening two trades in opposite directions at the same time each day:

  • one buy (long) trade
  • one sell (short) trade

Both trades use the same stop loss and take profit settings. If either trade remains open at the market close, it is closed at 4:00pm ET.

The analysis then tests multiple stop-loss and profit-target combinations to assess which setups would have performed best over a defined historical period.

How the backtest works

The strategy is tested using historical intraday price data on the S&P 500, with SPDR S&P 500 ETF (SPY) used as the underlying data source.

  • Stop loss and take profit distances are tested from 5 to 100 points
  • All combinations are evaluated systematically
  • Results are measured over a rolling 12-month (260 trading day) period
  • The same rules are applied consistently across all tested periods

This helps show how the strategy would have behaved under real historical intraday price movement, without changing the core rules from one period to the next.

What a backtest can tell you

A backtest does not predict the future, but it can reveal useful information about a strategy’s structure.

In particular, it can help show:

  • how stable or unstable the results are over time
  • which stop-loss and profit-target settings have historically performed better than others
  • whether a strategy is highly dependent on one narrow configuration
  • how much outcomes change when market conditions shift

For Twintraday, this is especially important because small adjustments to the stop or limit distance can materially change performance.

What the results suggest

The backtest results suggest that the strategy can behave very differently depending on the exact stop loss and take profit combination applied.

The main themes are:

  • there is no single fixed setup that remains optimal at all times
  • some stop and limit ranges have historically been more robust than others
  • very small parameter changes can significantly alter outcomes
  • settings that worked well in one period may lose effectiveness later

This is why the strategy is viewed through a rolling optimisation window rather than relying on one static historical result.

Why a rolling 12-month window is used

Markets evolve over time. A setup that performed strongly in one environment may not behave the same way after volatility, trend structure, or intraday movement patterns change.

Using a rolling 12-month window means the analysis is always focused on relatively recent market behaviour, while still using enough data to avoid drawing conclusions from only a short-term sample.

This makes the backtest more relevant to current conditions and more useful for ongoing analysis.

Important limitations of backtesting

Backtesting is valuable, but it has limitations and should be interpreted carefully.

  • past performance is not a reliable indicator of future results
  • live execution may differ from historical testing assumptions
  • broker pricing, spreads, and slippage can affect real outcomes
  • results based on SPY-derived data may differ from live trading on the US 500 index or related instruments

A backtest is best used as a framework for understanding behaviour and comparing configurations, rather than as a guarantee of future performance.

See the latest analysis

Twintraday provides daily updated analysis of the strategy using the most recent 12 months of data.

This allows you to see which stop loss and take profit combinations are currently performing best under recent market conditions.

View latest analysis

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How Twintraday Works

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Stop Loss and Take Profit

See how different stop loss and take profit distances can affect performance.

Buy and Sell at the Same Time

Learn how the simultaneous buy-and-sell structure works in practice.