The essential guide to investing by theme

There are many reasons people start investing. Some are looking to boost their income; others are building a pension pot to support them in retirement. Whatever their objectives, embracing an investment theme can help beginners achieve their goals by providing a clear, long-term strategy to follow.

This three-minute guide introduces the concept of themes, examines which investor type they suit and suggests several funds worth considering.

What are investment themes?

Investment themes are long-term structural trends that drive growth in certain areas and enable investors to achieve a specific objective. They are created by structural changes such as urbanisation, technological breakthroughs, regulatory changes and global catalysts. However, there are downsides to embracing themes. These include the risk of becoming concentrated in one area and the possibility of share prices being inflated by market hype.

How to play investment themes

• Identify a long-term trend
• Choose a fund that invests in them
• Set an investment time horizon
• Monitor regularly and adjust as necessary

Choosing your theme

An investment theme is anything that’s likely to benefit from a long-term trend. These can be driven by geopolitical events and consumer demand. For example, rising global conflict will fuel demand for military hardware, while the need for better internet will drive large-scale infrastructure projects. Meanwhile, political agreements, such as efforts to reduce our impact on the environment, will also create themes and patterns of change, such as people living longer. 

Four examples of long-term investment themes

Here are four investment themes we believe are worth considering, along with the reasons they should be considered, and how to access them.

Megatrends

Concept: The idea is to back companies heavily involved in the latest global trends, in the hope that these businesses will benefit in the long term. Artificial intelligence, climate change, and healthcare are among the biggest areas tipped to transform how we live and work. Of course, the potential downside is that all these predictions can be wrong. What was thought to be a long-term trend could fizzle out or be superseded by a different approach.

Read more: Megatrends unveiled: the power of thematic investing

How to do it: One approach is to choose a fund – or funds – that you believe are set for phenomenal growth over the next few years. For example, the Liontrust Sustainable Future Global Growth fund uses a thematic approach to identify the key structural trends that are expected to shape the global economy. Information technology has the largest sector allocation, at almost 30%*, followed by healthcare, financials, and industrials. 

Of course, you can focus on one key trend. For example, the Allianz Technology Trust believes technology spending will continue to grow, driven by long-term megatrends. Discover the dynamic world of technology with Mike Seidenberg on the Investing on the go podcast.

Infrastructure 

Concept: Invest in companies involved in projects aiming to improve transport links, communication systems and the provision of utilities. Much of this demand is in emerging markets that have never had such services, although replacing and updating programmes are providing opportunities in developed areas. The world faces a $64 trillion cost of updating infrastructure, according to a report from Aberdeen**. This includes upgrading roads, railways, energy grids and broadband connections.

How to do it: This is an increasingly popular theme, so there are now dedicated funds. For those wanting international exposure, we like M&G Global Listed Infrastructure. Its investments can include everything from utilities and toll roads to health and mobile towers. This means it looks beyond traditional areas to embrace more modern infrastructure.

An alternative is TM Gravis UK Infrastructure Income. This provides investors with exposure to UK-focused projects and targets an annual income of 5%. Power & utilities has the largest allocation of 53%, followed by 16% in social infrastructure and almost 10% in transportation & logistics systems***.

Ageing population

Concept: The idea is to make money by investing in companies that make products or services that will benefit from the ageing global population. This can include everything from healthcare companies to businesses that help people live longer and spend their retirement income. Longer life expectancy and declining birth rates mean that one in six people worldwide will be 65 or older by 2050, according to a Morgan Stanley report****.

How to do it: There are plenty of companies that stand to benefit from an ageing population. However, one of the most obvious is the healthcare sector. The Polar Capital Global Healthcare Trust invests in companies within four main sub-sectors: pharmaceuticals, biotechnology, medical technology, and healthcare services. 

Interestingly, the portfolio is split into growth and innovation. The growth part, which accounts for 90%, is in larger businesses, while the remaining 10% is in smaller firms with greater potential. Currently, the largest holdings include Eli Lilly, AstraZeneca, and Abbott Laboratories with pharmaceuticals accounting for roughly a third of the portfolio***.

Environmental 

Concept: Put your money into companies working to protect our planet, such as combating climate change and developing alternative energy sources. This is one of the most important long-term themes, and governments around the world have committed to environmental goals. There is also an added benefit of embracing this important global objective: making money at the same time as saving the world.

How to do it: We like the Ninety One Global Environment fund. This is a global equity portfolio that invests only in companies that contribute to decarbonising the global economy. This fund is set to benefit from the $2.4 trillion that must be spent each year to meet global temperature goals.

You can also embrace the environmental theme by investing in portfolios focused on specific areas. For example, we like the Regnan Sustainable Water and Waste fund. As its name suggests, this invests in companies that provide solutions to the various global water and wastewater challenges.

Read more: Ethical investment funds: a practical UK guide

*Source: fund factsheet, 31 October 2025

**Source: Aberdeen investments, 26 June 2025

***Source: fund factsheet, 30 September 2025

****Source: Morgan Stanley, 21 July 2025