The professional's edge: backtesting, optimization, and going live.

The Hard Part

A profitable backtest is not the same as a good strategy. This module teaches you how to tell the difference.

I'm up $60,000 because I know how to backtest.

Every strategy, before a single dollar went live, got tested. But I also never trusted a backtest the way a lot of people do. Not as proof that something works. A backtest tells you a strategy wasn't obviously broken in the past. That's it. Whether it works going forward is a separate question.

Most people learn this the hard way. You build a strategy. You run a quick test. It shows 42% returns over the last two years. You're excited. You deploy it with real money. Three months later, you've lost 25%.

That's not bad luck. It's a misunderstanding of what a backtest actually tells you, and what it doesn't.

This module covers everything you need to evaluate your strategy honestly and optimize it without fooling yourself. By the end, you'll know exactly what separates a strategy worth deploying from one worth deleting.

"A good trading strategy isn't just a strategy that makes money. You have to consider your alternative investment ideas."

The benchmark is simple: over the past 100 years, the S&P 500 has averaged roughly 10% per year. Building a trading strategy is a lot of work. If your strategy doesn't consistently beat that on a risk-adjusted basis, you'd be better off buying one ETF and doing nothing.

Performance Metrics

Three numbers that actually tell you whether a strategy is good.

Watch · What Makes a Trading Strategy Good? — Benchmarks, Sharpe Ratio & Drawdown

Most beginners evaluate strategies on a single metric: total return. But total return without context is nearly meaningless. A strategy that returned 40% but had a -60% drawdown at one point is not the same as a strategy that returned 28% with a -17% drawdown. The second one is probably better.

Professionals use three core metrics to evaluate risk-adjusted performance:

NexusTrade QuickTest — Magnificent Seven rebalancing strategy: +27.6% total return, Sharpe 1.07, Sortino 1.59, Max Drawdown -17.3%. All three metrics in one view.

You can run this same test on your own strategy with a NexusTrade Premium account. Connect a Public.com brokerage account to get 3 months free.

The Magnificent Seven rebalancing strategy above shows what a solid result looks like. +27.6% total return. Sharpe of 1.07 means every unit of volatility is being rewarded. Sortino of 1.59 means downside volatility is well-controlled. Max drawdown of -17.3% is painful but survivable. Most people can hold through that.

Stress Testing

What a backtest actually tells you. And the two ways it can lie.

Watch · What is Backtesting? — How to Test Your Trading Strategy

A backtest is a historical replay of how a set of trading rules would have performed over a specific period of the past. It's one of the most powerful tools in algorithmic trading. And one of the most dangerous if you misread it.

NexusTrade full backtest: one year of historical performance. Solid metrics overall, but notice the recent decline. This is why you test across multiple market conditions.

Lie 1: Past performance = future performance

Stock market returns are non-stationary. A strategy that worked brilliantly in a bull market may be catastrophic in a bear market. A strategy perfectly tuned to the 2020–2024 AI boom may have no edge at all in the next cycle. The backtest tells you how it would have worked, not how it will work.

Lie 2: A good backtest means it will work everywhere

Test your strategy across different time periods, not just the one where it looks best. A strategy that outperforms in every 1-year window from 2020 to 2024 is very different from one that only looks good from 2021 to 2023. Robust strategies hold up. Fragile ones don't.

Lie 3: The backtest assumes perfect fills

Most backtests assume you bought and sold at the exact closing price with zero fees. In reality, there's a bid-ask spread on every trade, and large orders move the market against you. This is called slippage. A strategy that trades frequently in small-cap stocks can look great in backtest and underperform significantly live because the backtest never paid the spread.