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Alfonoso Peccatiello recently wrote an interesting piece on portfolio risk management, starting with a quote from Steve Cohen:

‘’I compile statistics on my traders. My best trader makes money only 63 percent of the time. Most traders make money only in the 50 to 55 percent range. That means you’re going to be wrong a lot. If that’s the case, you better be sure your losses are as small as they can be, and that your winners are bigger.’’

If you think that is a poor “batting average,” we can gain some perspective by looking at the top-10 highest batting averages in Major League Baseball. You should notice that the best baseball hitters in history only succeeded about 35% of the time they went to bat.
 

Crucially, Cohen’s quote captures the essence of portfolio risk management. Even top-tier professionals are wrong nearly half the time. That reality is uncomfortable but essential and is something that all investors should embrace. In other words, you will often be wrong, begging the question: how do you survive? The answer lies in risk control. Cohen’s firm, Point72, has outperformed because his traders limit losses and allow winners to grow.

That isn’t luck. That is the process.

Most investors focus on being right by obsessing over stock picks, timing, and macro predictions. However, here is the hard truth you must learn:

Accuracy is overrated. Survival is underrated.

Your real edge comes from limiting damage when you’re wrong and maximizing gains when you’re right, which is the very foundation of any risk plan. You will lose. You must build your system around that fact, which encompasses three crucial facets:

1. Position sizing,
2. Stop-loss rules, and;
3. A strict discipline that is easily repeatable.

Ultimately, that blueprint will be what separates long-term success from failure. Risk management isn’t about avoiding loss. It’s about ensuring the losses you take don’t destroy you.

Let’s discuss these vital strategies in more detail.
 

The Role of Position Sizing

Position sizing is your primary tool to control risk. Research shows it drives over 90 percent of a strategy’s risk-adjusted return variance. That statistic tells you strategy selection matters less than how you size your trades. The chart illustrates that with poor sizing, even a profitable edge fails.
 

Imagine two strategies with identical entry and exit signals. Strategy A risks 1% of capital per trade while strategy B risks 5%. A drawdown hits both. The 5% risk account falls 25% after five consecutive losses, while the 1% account loses only 5%. The difference in recovery time is dramatic.

Position sizing isn’t just about math. It’s about psychology. As we discussed in that linked article, we will all make bad choices from time to time. The goal is to try to make bad choices that don’t have an outsized effect on your investment outcome. One of the most significant benefits of keeping losses small is that they lead to less emotional stress, which limits our behavioral biases of “loss avoidance.”

So, how do you size a position in your portfolio? Let’s use $NVDA (NVIDIA Corporation) as an example, with a $100,000 investment account and risk control principles with a share price of $174.18 per share using a 1% risk per trade framework:
 

As an investor, you must adjust your risk profile to your own specifications; this example just gives you the framework to do it. This example risks $1,000, or 1% of the account, while putting approximately $12,370 to work in NVDA. However, the most CRITICAL point is that the stop-loss level MUST BE maintained.

That structure ensures losses remain manageable, aligning with robust risk management practices. However, most investors’ biggest mistake is failing to sell when the stop-loss is triggered.

A rule only works if it is followed strictly.
 

Loss Limits and Managing Overall Risk

As noted, cutting losses and honoring stop-loss levels are non-negotiable as a trader. You don’t get to argue with the market; you only get to decide how much pain you’ll take.

For example, Steve Cohen’s traders survive because they cut losers quickly. Bill O’Neil used a 7% to 8% stop loss. Warren Buffett said, “Rule #1: Don’t lose money. Rule #2: Don’t forget Rule #1.” Millennium Management imposes strict loss caps per trader. Break the cap, lose your capital allocation. That policy helped them rack up $56 billion in gains while keeping volatility low.

Those are not empty slogans. They are the rules that they live by.

Use stop-losses on every trade. Most importantly, your stop-loss should be predefined and sacred before you make the initial trade. Furthermore, once the trade is implemented, never move the stop farther away, which only widens your loss.

If you are unsure how to apply stop losses to your position, use a simple moving average, like the 50, 100, or 200-day moving average (DMA). These averages give you an easy and visible stop-loss that adjusts as the price of your holding rises. The chart below shows the S&P 500 index with the 50, 100, and 200-DMA and the percent loss to each level. What moving average you use is up to you; however, ensure it fits within your realistic “loss tolerances.”
 

(Click on image to enlarge)

There are other things you can do to add further levels of protection:

• Stress test your portfolio.
• Run simulations for interest rate spikes, geopolitical events, or liquidity crashes.
• Assume the worst. Ask yourself what you’ll do if it happens.
• Keep cash on hand. Liquidity gives you power when others are forced to sell.
• Hedge when asymmetries appear.

The crucial takeaway is to use every tool available for portfolio risk management, whether it is stop-losses, stress tests, rebalancing, hedges, or liquidity buffers.

Layer them. These are your lifelines.
 

Portfolio Risk Management Relative to the Market

Portfolio risk management doesn’t live in a vacuum. You must manage it relative to the broader market.

To do that, you need to use volatility as a key input. The VIX sat in the 15 to 18 range in July 2025. That’s low. But low doesn’t mean safe. Low volatility often signals complacency. When volatility is cheap, it pays to buy insurance.
 

(Click on image to enlarge)

Likewise, investors must separate perceived risk from actual risk. Volatility may feel like danger, but it is often simply price movement around a trend. Actual risk lies in permanent capital loss, overconcentration, or misalignment with one’s time horizon and objectives.

As we discussed previously, volatility begets volatility. Periods of low volatility always lead to high volatility, like now. However, the opposite is also true. The trick is navigating the periods of high volatility well enough to participate in the extended periods of low volatility. Ray Dalio, founder of Bridgewater Associates, advocates for a similar analytical approach to risk:

“If you’re not worried, you need to worry. And if you’re worried, you don’t need to worry.”

In other words, constant vigilance and preparation are more productive than panic. Investing during periods of uncertainty can be dangerous; however, there are some steps to take when investing in uncertain markets.

Furthermore, watch market internals. Currently, the market is hitting new highs with weak breadth while margin debt is rising sharply. These are red flags worth paying attention to, and they suggest a level of market fragility.

Correlation is another tool. When assets move together, risk rises. Monitor this. If everything you own starts trading the same, reduce risk.

Most critically, ask yourself: “Is my portfolio positioned for how the market behaves now rather than how I think it should behave?”

That humility protects your capital.
 

Bringing It All Together

You will be wrong often. Portfolio risk management turns that weakness into a strength, giving you staying power in the game. In our previous discussion of “Investing Like Spock,” we noted:

“Reacting emotionally to short-term moves often destroys long-term returns. Spock’s strength was never his speed, but his steadiness.

“Logic is the beginning of wisdom, not the end.”

The ability to step back, re-evaluate with clarity, and follow a predetermined investment process keeps portfolios aligned with goals.

Discipline and patience are a strategic advantage in portfolio risk management.

Here are ten rules from professionals who have mastered the game:

1. Limit risk per trade to 1–2 percent. Small losses preserve capital. That keeps you in the game.
2. Use stop‑losses consistently. Bill O’Neil used 7–8 percent stops. Buffett insisted on not losing. Cut losers fast.
3. Diversify across strategies and markets. Michael Dever used risk parity across strategy‑market cells. That prevents dominance.
4. Use firm‑style stop limits. Millennium applies strict limits per desk, per trader. Breaches trigger capital removal. That enforces discipline.
5. Adjust sizing by volatility regime. Trend followers scale down in turbulence, scale up in steady trends.¹¹ That adapts to the market state.
6. Hedge asymmetries. Use options to protect from downside while maintaining upside. Goldman recommends put spreads when asymmetry rises.
7. Develop crisis buffers. Maintain cash for opportunities and stress. Scenario stress testing builds resilience.
8. Use trading journals and refine habits. Successful traders record every trade. Knowing your tendencies avoids repeated mistakes.
9. Train mental risk awareness. Susquehanna uses poker to build probabilistic thinking under uncertainty. That sharpens emotional control.
10. Commit to your rules. Wyckoff insisted on stop placement in every trade. Discipline beats guesswork.

Your system should be written down, reviewed, and lived by. Any adjustments must come from the data, rather than emotions.

In the end, discipline always wins. Portfolio risk management is not exciting, but it’s why some investors survive while others vanish.

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