What Would A Brexit Mean For The FTSE 100?

Should you sell up and walk away from the FTSE 100 (INDEXFTSE:UKX) until after the referendum has passed?

The content of this article was relevant at the time of publishing. Circumstances change continuously and caution should therefore be exercised when relying upon any content contained within this article.

You’re reading a free article with opinions that may differ from The Motley Fool’s Premium Investing Services. Become a Motley Fool member today to get instant access to our top analyst recommendations, in-depth research, investing resources, and more. Learn More.

With less than four months to go until the referendum on Britain’s membership of the EU, the outlook for the FTSE 100 is uncertain because we’re entering uncharted territory. The outcome of the vote seems likely to be very close and this has the potential to cause weaker investor sentiment in the coming months.

So it seems likely that the FTSE 100’s performance will be held back between now and referendum day. After all, this could be one of the biggest decisions (both politically and economically) for the British people in recent decades and it’s likely to have a huge impact on the domestic economy.

Investors considering buying shares in FTSE 100 companies may decide to hold off for a few months to see what the result is. Similarly, investors nervous about the outlook for the global economy may see the prospect of a Brexit as confirmation that now isn’t the right time to be holding shares and may seek the relative safety of cash or a supposed store of wealth such as gold.

Bulls and bears

As mentioned, uncertainty is likely to be a key theme between now and the vote, so a major bull run seems unlikely (although it can never be ruled out). And if Britain does decide to leave the EU, then it’s very much a case of ‘all bets are off’. In other words, what happens to the FTSE 100 and the economy on Britain’s exit is difficult to predict since it would be unique.

Clearly, both sides of the debate are quoting various figures for employment levels, business relocation (or lack of) and GDP levels that they say would be impacted by Britain leaving or staying. Whether these are accurate or not is up for debate, but when it comes to the FTSE 100, none of this may be all that relevant.

International outlook

That’s because the FTSE 100 is a truly international index that’s far less reliant on the performance of the UK economy than on the global outlook. A fall or rise in employment levels, GDP or in multinationals located in the UK is unlikely to have a major impact on FTSE 100 earnings since its constituents are geographically diversified. And while the UK economy matters greatly to Britons, the US and China remain the major players when it comes to global economic growth.

EU economy

The caveat to that viewpoint, however, is the performance of the EU economy itself. If Britain were to leave then there’s a chance the EU would offer worse long-term growth prospects than currently. Why? As the fifth largest global economy, Britain has a positive overall impact on EU trade and economic activity. Without Britain as a member, it’s possible for the EU to suffer from a similar kind of uncertainty as Britain would do on a Brexit, which could mean a worsening macroeconomic outlook. This would be bad news for the global economy and for the FTSE 100 too.

Of course, history tells us that Britain and the FTSE 100 have endured greater challenges than the question of EU membership. With share prices being low, any further discount could represent an even better time to buy quality stocks for the long term. While their performance may be volatile in the short run, longer term, the UK, EU and world will continue to grow even if trading blocs and political unions change, fade and ultimately disappear.

Peter Stephens has no position in any shares mentioned. The Motley Fool UK has no position in any of the shares mentioned. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors.

More on Investing Articles

Group of young friends toasting each other with beers in a pub
Investing Articles

FTSE 100 shares: has a once-a-decade chance to build wealth ended?

The FTSE 100 index has had a strong 2025. But that doesn't mean there might not still be some bargain…

Read more »

Passive income text with pin graph chart on business table
Investing Articles

I asked ChatGPT for its top passive income ideas for 2026 and it said…

Stephen Wright is looking for passive income ideas for 2026. But can asking artificial intelligence for insights offer anything valuable?

Read more »

Woman riding her old fashioned bicycle along the Beach Esplanade at Aberdeen, Scotland.
Investing Articles

Here’s how a 10-share SIPP could combine both growth and income opportunities!

Juggling the prospects of growth and dividend income within one SIPP can take some effort. Our writer shares his thoughts…

Read more »

Tabletop model of a bear sat on desk in front of monitors showing stock charts
Investing Articles

The stock market might crash in 2026. Here’s why I’m not worried

When Michael Burry forecasts a crash, the stock market takes notice. But do long-term investors actually need to worry about…

Read more »

Person holding magnifying glass over important document, reading the small print
Investing Articles

Is this FTSE 250 retailer set for a dramatic recovery in 2026?

FTSE 250 retailer WH Smith is moving on from the accounting issues that have weighed on it in 2025. But…

Read more »

Young Black woman using a debit card at an ATM to withdraw money
Investing Articles

I’m racing to buy dirt cheap income stocks before it’s too late

Income stocks are set to have a terrific year in 2026 with multiple tailwinds supporting dividend growth. Here's what Zaven…

Read more »

ISA Individual Savings Account
Investing Articles

Aiming for a £1k passive income? Here’s how much you’d need in an ISA

Mark Hartley does the maths to calculate how much an investor would need in an ISA when aiming for a…

Read more »

Two business people sitting at cafe working on new project using laptop. Young businesswoman taking notes and businessman working on laptop computer.
Investing Articles

Is investing £5,000 enough to earn a £1,000 second income?

Want to start earning a second income in the stock market? Zaven Boyrazian breaks down how investors can aim to…

Read more »