Will the FTSE 100 be unaffected by Brexit?

Will shares in the FTSE 100 (INDEXFTSE:UKX) react negatively to Britain leaving the EU?

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 various commentators, institutions, politicians and investors having differing views on the effects of Brexit, it may feel as though it’s impossible to determine exactly what would happen to share prices if it were to happen. On the one hand, this is perhaps to be expected since Britain leaving the EU would be an unprecedented event and the after-effects of such events are impossible to accurately predict. However, on the other hand, there are perhaps some reasonable assumptions that can be made.

Clearly, the FTSE 100 is an international index. A quick glance at its constituents confirms this, with a large number of them being companies that operate in all four corners of the globe. As a result of this, whether the UK economy grows or shrinks is perhaps not their most important consideration, with markets such as the US and China being far more significant to their long-term success.

Due to this, it could be argued that the FTSE 100 won’t be hurt by Brexit. Companies which rely on the UK to a greater extent (perhaps those in the FTSE 250 or smaller companies, for example) may be hit harder since uncertainty regarding British GDP growth will probably be higher in the event of Brexit. But for most FTSE 100 companies, it may make surprisingly little difference to their performance in the short run.

Furthermore, share prices tend to price-in risk. In other words, if there’s an event on the horizon that could increase risk, then shares will generally trade lower to reflect this. That could be the current situation with the FTSE 100, with the index having fallen by around 5% in the last month. Therefore, while Brexit may cause further weakness, it may already be priced-in to an extent.

Impact worldwide

Of course, the above discussion doesn’t take into account the global economy and the potential effects of Brexit on world GDP growth. Clearly, the EU is performing relatively poorly at the moment from an economic standpoint and if Britain was to leave then the region could see its performance deteriorate.

At a time when the US is raising interest rates and China is enduring a somewhat painful transition towards a consumer-focused economy, this additional disappointment could be enough to send investor sentiment south. In such a scenario the FTSE 100 could see its price level fall as the outlook for global GDP growth becomes increasingly uncertain.

Whether Brexit happens or not, the fact remains that the FTSE 100 faces major risks on a daily basis. An obvious example of this is 9/11, which was a completely unexpected event that caused the index to decline heavily. While such events are thankfully extremely rare, events that cause the FTSE 100 to fall in value do happen and can’t always be foreseen by investors.

As such, investing in the FTSE 100 is inherently risky and capital can be lost at any time. Perhaps the difference with the EU referendum is that it’s a known unknown and even if it does cause the FTSE 100 to shed a large number of points, the index is almost certain to recover – just as it always has.

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

Thoughtful man using his phone while riding on a train and looking through the window
Investing Articles

Here’s how to try and create a £10,000 second income portfolio

Millions of UK investors use the Stocks and Shares ISA to build wealth and eventually take a second income. Dr…

Read more »

ISA Individual Savings Account
Investing Articles

3 steps to aim for a lifetime of passive income from a new ISA

It's that time of year again when we're all planning how make the most of our new ISA limit to…

Read more »

Three signposts pointing in different directions, with 'Buy' 'Sell' and 'Hold' on
Investing Articles

A once-in-a-decade chance to buy Nvidia shares at a discount?

Nvidia shares are trading at a discount to the S&P 500 for the first time in 10 years. Is it…

Read more »

Hand of person putting wood cube block with word VALUE on wooden table
Investing Articles

This FTSE 100 stock’s crashed over 25%. But could it be an amazing opportunity for income and growth?

There’s one FTSE 100 stock that’s been badly affected by the conflict in the Gulf region. But could this be…

Read more »

Man hanging in the balance over a log at seaside in Scotland
Investing Articles

How many Aviva shares must I buy to give up work and live off the income?

Aviva shares are on track to pay a 6.7% yield in 2026, generating a highly tempting stream of passive dividend…

Read more »

Typical street lined with terraced houses and parked cars
Investing Articles

£5,000 invested in Taylor Wimpey shares 5 years ago is now worth…

Taylor Wimpey shares haven’t been a terrific investment over the last five years, but has this share price weakness created…

Read more »

ISA coins
Investing Articles

Looking for dividend stocks for a new ISA? These 2 are among the most popular in 2026

Some investors worry about where share prices are going. Others just sit out volatility and rely on income from dividend…

Read more »

Young female analyst working at her desk in the office
Investing Articles

£500 invested in Legal & General shares 5 years ago is now worth…

Investors are rushing to buy Legal & General shares as the dividend yield hits 8.9%! But how much money are…

Read more »