Thematic Investing Examples: 12 Themes and How to Track Them

Thematic investing is the practice of organizing a portfolio around a long-running idea or trend rather than around a sector label or a country. Instead of buying "technology," you might build a basket around "artificial intelligence infrastructure" or "the shift to clean energy," pulling together companies from different sectors that all stand to be shaped by the same force. Themes make a portfolio legible: every holding is there for a reason you can state in a sentence. This article gives twelve concrete theme examples and shows how to turn any of them into a weighted index you can backtest and track. It is educational and is not investment advice.

Twelve theme examples

These are illustrative starting points, not recommendations. The value of a theme is that it gives your index a clear identity, which makes it far easier to define, maintain, and interpret later.

Turning a theme into an index

A theme is an idea; an index is a rulebook. To bridge them, translate the theme into concrete inclusion rules. For "cybersecurity," you might specify "publicly listed companies whose primary revenue comes from security software or services." That gives you a defensible universe rather than a vague vibe. Write the rule down so anyone, including future you, could reproduce the list. This step is what separates a real thematic index from a loose watchlist.

Weighting a thematic basket

Once you have the members, decide how much of each to hold. Thematic baskets are often equal weighted, because the point is exposure to the theme broadly rather than to whichever member happens to be largest. Equal weighting stops one giant from turning your "AI theme" into a bet on a single company. Alternatively, a capped market-cap scheme keeps some size logic while preventing dominance. You can compare approaches in market cap versus equal weight and try each with different weighting schemes.

Set rebalancing so the theme stays intact

Themes evolve. Companies pivot into or out of the trend, and within an equal-weighted basket the winners drift to outsized weights. A periodic rebalance, such as quarterly, keeps the basket true to its design, and a periodic review of membership keeps the theme current. Decide both cadences up front so the index does not quietly turn into something else.

Backtest and track the theme

With the rulebook set, backtest the theme over history to understand its character: how volatile it was, how deep its worst drawdown ran, and how it moved relative to a benchmark. Thematic baskets can be more volatile than the broad market because they are concentrated in one idea, and a backtest makes that visible. Keep two things in mind: backtested figures are hypothetical historical performance, and past performance does not guarantee future results; and a theme that looked strong in one period may not repeat. Then track the index forward and compare it to a fair benchmark using benchmark comparison, so you can see whether the theme is adding anything beyond the general market.

A worked example

Suppose you want a clean-energy index. You define the universe as "listed companies with most revenue from solar, wind, or grid storage," select ten names that qualify, weight them equally at 10 percent each, cap any name at 15 percent, and rebalance quarterly with a review of membership twice a year. You set a base value of 100, backtest it, and track it against a broad benchmark. That is a complete thematic index, ready to study.

If you want to turn a theme into a trackable index without spreadsheets, Indexes lets you assemble a weighted basket of stocks or crypto around any theme, backtest it against real history, and track its level against a benchmark. It is built for learning and measurement, not trading, and nothing here is investment advice.