Risk management

How to Diversify a Trading Portfolio and Reduce Risk

Astron Team · 09/24/2026 · 4 min read

Diversifying means spreading capital across assets that don't all react the same way to the same event. The goal isn't to eliminate risk — that's impossible in any market — but to prevent a single negative factor from bringing down the result of the entire portfolio at once.

Why putting everything into a single asset is a high-risk choice

Suppose a R$ 10,000.00 portfolio invested entirely in shares of a single company. A company-specific event — a bad quarterly result, a regulatory problem, the departure of a key executive — can drag down the value of the entire portfolio at once, even if the rest of the market is stable or rising. Diversifying doesn't eliminate this kind of event, but it limits the damage it causes to the total invested.

Diversification across asset classes

Stocks, fixed income, currencies, and commodities tend to react differently to the same economic scenarios. During a period of high interest rates, for example, fixed-income bonds tend to benefit directly, while stocks more dependent on cheap credit can suffer. A R$ 10,000.00 portfolio split into R$ 5,000.00 in stocks, R$ 3,000.00 in fixed income, and R$ 2,000.00 in a basket of currencies or commodities tends to suffer less from a single economic scenario than the same amount concentrated in one class alone.

Diversification within the same class

Even within stocks, concentrating everything in a single sector reproduces the same problem on a smaller scale — an event affecting that entire sector (a regulatory change, a raw-material crisis) hits the whole portfolio. Spreading across different sectors (energy, consumer goods, technology, banking, for example) reduces this dependence on a single specific sector cycle.

Time-frame diversification

Combining trades with different time frames — some very short-term, others medium or long-term — also reduces dependence on a single market regime. A short-term strategy can work well in a sideways market and poorly in a strong trend, while the opposite tends to be true for medium-term trend strategies. Having both approaches at the same time, with capital allocated to each, smooths out periods when one of them isn't performing.

The mistake of over-diversifying

Excessive diversification also has a cost: spreading capital across 40 different assets, in amounts so small that none of them really moves the portfolio's result, dilutes both risk and potential gain, while also making it impractical to track each position. There's a balance point between excessive concentration and excessive diversification, and it varies depending on the capital available and the time you have to track each position.

How to build a first diversified allocation

• First, define the maximum percentage of total capital that a single position can represent — for example, 15% to 20%.
• Spread across at least two or three different asset classes, not just among similar assets within the same class.
• Review the allocation periodically — the diversification from a month ago may have concentrated on its own, as some assets rise more than others.

Diversifying well doesn't guarantee profit or eliminate the possibility of loss — it only reduces the chance of a single specific event compromising a large share of the capital at once. It's a risk management tool, not a profit strategy, and it works best when planned before any position is opened, not as a reaction after a concentrated loss.

Correlation: the detail many diversification attempts ignore

Two different assets only truly diversify a portfolio if they don't always move in the same direction at the same time — which is measured by the correlation between them. Holding positions in five different bank stocks looks diversified because it involves distinct companies, but if they all react the same way to an interest rate change, the real diversification is much smaller than the number of assets suggests. It's worth checking, even in a simple way, whether the chosen assets tend to rise and fall together or independently before considering the portfolio truly diversified. A good periodic exercise is to review, every quarter, how many positions in the portfolio reacted the same way to the same recent event — if the answer is "almost all of them", that's a sign the diversification is more apparent than real, even with several different assets on the list.