Step 3: Choose a Strategy Based on Your Style — and Understand WHY They Work

QMA Academy Team. In Step 2, you identified your style — how much time you have, how long you want to hold positions, how much volatility you can handle. Now we'll translate that style into specific strategies. And most importantly: we'll explain why different families of strategies have historically worked — because without understanding the principle, you're just copying a formula that will stop working when you least expect it.

This is not a "buy this" list. It's a map of schools of thought — from Graham to O'Neil to Jim Simons' quant funds — and a guide on how to distinguish a genuine strategy from repackaged marketing.

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What is a Strategy and What is EDGE

A strategy is a repeatable, documentable way to select stocks, when to enter them, and when to exit them. The key word is repeatable — if you can't write your rules on paper so that someone else can understand them tomorrow, you don't have a strategy, you just have feelings.

Edge is the reason why your strategy should, on average, earn more than it risks. Edge is not "I have a good intuition." Edge is a statistically demonstrable imbalance — a situation where the market behaves more predictably than it should by chance.

Examples of real edges confirmed by science and practice:

• Momentum: stocks that have risen in the last 6–12 months tend to continue rising (described by Jegadeesh & Titman, 1993).
• Value: cheap stocks (low P/E, P/B) have historically outperformed expensive ones (Fama & French).
• Quality: companies with high returns on capital and stable margins survive longer.

★ Insight: Edge is always probabilistic, not certain. A good strategy doesn't win every trade — it wins on average over many trades. If you judge it by the last three trades, you're judging noise, not signal. This is the most common beginner's mistake: "this strategy doesn't work" after four losses, even though it has a long-term 58% success rate.

Why Every Strategy Needs a Backtest — and Where the Trap Lies

A backtest means: I take a strategy, run it on historical data (say, 5–20 years back), and measure how it would have performed. Without a backtest, a strategy is just a story. With a backtest, it's a measurable hypothesis.

But a backtest can easily be falsified to oneself — not intentionally, but out of naivety. Two deadly traps:

1. Over-optimization (curve-fitting / overfitting). When you mine the strategy rules until they fit exactly to past data, you create a beautiful chart that fails immediately in reality. Example: "buy when RSI falls below 27.3 and it's Tuesday and the month ends on an even number." Such finely tuned rules describe past noise, not future law. The more parameters and the more precise the numbers, the more suspicion.

2. Look-ahead bias. When a backtest accidentally uses information that you wouldn't have had on that day. Classic: "sort stocks by their annual return and buy the best" — but you only know the annual return after a year. On the day of entry, you didn't know it. The backtest then shows fantastic numbers that you can never replicate.

★ Insight: The defense against both traps is an out-of-sample test — you tune the strategy on one part of the data (e.g., 2010–2018) and test it on another, untouched part (2019–2024). If it works even where you didn't tune it, there's a chance it has a real edge. If it only works on the tuning data, it's a curve-fit. At QMA, we therefore distinguish live results vs. backtest (see /predictor) — live data is the hardest out-of-sample test that exists because it cannot be rewritten.

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Seven Main Families of Strategies

None of them is "the best." Each works in a different market phase and suits a different type of person. We'll go through the logic of when a given family shines and when it suffers, and for whom it is.

1. MOMENTUM / breakout — "buys strength"

Logic: Strength begets strength. A stock that breaks to a new high from a good consolidation often attracts more buyers (institutional funds, index flows), and the trend continues. You buy what is already rising, not what is "cheap."

Legends and concepts unknown to retail:

• William O'Neil — CANSLIM: 7 criteria (Current earnings, Annual earnings, New product/management, Supply & demand, Leader, Institutional sponsorship, Market direction). O'Neil empirically found that the biggest winners had a specific fundamental profile before their meteoric rise — accelerating earnings and institutional buying.
• Mark Minervini — SEPA & VCP: "Volatility Contraction Pattern" — the price gradually calms down before a breakout (candles narrow, volume dries up), signaling that sellers are exhausted. Minervini waits for this contraction.
• Nicolas Darvas — Darvas Box: a dancer who made a fortune in the 50s by tracking price "boxes" and buying at the breakout of the upper edge.

When it works: in clear bull trends and rotations where leaders have room to run.
When it suffers: in choppy, sideways markets — breakouts fail (false breakouts) and the strategy bleeds small losses.
For whom: an active trader who can handle quick exits, stick to stops, and doesn't mind buying "expensive."

2. VALUE — "buys cheap"

Logic: The market sometimes overshoots downward and values a good company below its true worth. When you buy with a margin of safety, time works for you.