Diversification (Diversifikation)
Diversification is spreading money across assets that don't all lose value at the same time, so a decline in one holding is offset by stability or gains in others. It reduces the risk of a single company, sector, or country determining the outcome, in exchange for giving up the chance of an outsized gain from one lucky, concentrated bet.
Why it matters
Most portfolio-construction concepts in German personal finance build on diversification: whether concentration risk, home bias, or rebalancing apply to a given holding all depend on how spread out it already is. It's also the practical reason index-tracking ETFs (Exchange Traded Funds) exist — a single fund can hold hundreds or thousands of companies, doing in one purchase what would otherwise take dozens of individual trades. Understanding diversification first makes those downstream concepts, and the mechanics of any specific asset class, easier to evaluate on their own merits.
Worked examples
1. Concentration versus spread — a single company versus many. An investor puts €10,000 into shares of a single company. If that company has a bad year and loses 40% of its value, the investor loses €4,000 (€10,000 x 0.40). The same €10,000 spread across an index of 500 different companies is affected only to the extent the average company's value fell that year — an illustrative 8%, a loss of €800 (€10,000 x 0.08). Diversification doesn't prevent a market-wide decline; it removes the extra risk of one company's fortune deciding the whole result.
| Portfolio | Composition | Loss in a bad year (illustrative) |
|---|---|---|
| Concentrated | €10,000 in one company | -40% -> -€4,000 |
| Diversified | €10,000 across 500 companies | -8% average -> -€800 |
2. Diversifying across asset classes and geography. A portfolio holding companies from a single country carries country-specific risk — a national recession, currency shock, or regulatory change hits the whole portfolio at once. Spreading the same amount across companies in dozens of countries, and mixing equities (Aktien, company shares) with lower-volatility asset classes such as bonds, narrows the range of possible outcomes further. The tradeoff runs both ways: a concentrated bet that happens to pay off outperforms a diversified portfolio, but there's no way to know which concentrated bet will pay off in advance.
Check yourself
An investor holds shares in 20 different companies, but all 20 are airlines based in the same country. Fuel prices spike and airline stocks fall sharply industry-wide. What does this show?
A €20,000 portfolio is spread across 400 companies in different countries and industries. In a downturn, the average value of those companies falls by 6%. How many euros does the investor lose?
Which of the following genuinely increase diversification in a portfolio? Select all that apply.
What is the main tradeoff of diversifying a portfolio?