One of the largest rifts opened by last Thursday’s momentous vote to leave the EU has been between the international-looking large-cap FTSE 100 and the rest of the UK stock market. While mid and small-caps will likely be in for a sustained battering due to a weak pound, lower investment and the ever-looming threat of a domestic recession, large-caps look set to ride out the storm relatively comfortably.

This is because FTSE 100 constituents bring in more than 75% of their revenue from overseas. When these dollars, yen and euros are converted to pounds come earnings season, expect bumper profits for international firms. Likewise, fund managers who need exposure to UK shares but are bearish on the medium-term outlook for small and mid-size firms will likely increase their positions in large caps.

Currency exchange boost

The combination of a weaker pound helping earnings and inflows of institutional money could set the stage for continued success at firms such as ARM Holdings (LSE: ARM). ARM is one of the largest UK exporters, with only £5.1m out of its £968.3m worth of sales in 2015 coming from the UK. If the pound continues to slip in value against other major currencies, ARM could beat its 22% year-on-year jump in sterling revenue recorded in Q1.

Of course, investors who follow the Motley Fool’s playbook know that short-term currency movements shouldn’t be the only reason for buying a stock. Thankfully, ARM has plenty of long-term potential too. The company has 85% market share in mobile computing chips, for devices such as smartphones and laptops, and is moving quickly into the growth market of connected devices. A dominant market position combined with 48.6% operating margins, £1bn in net cash and a substantial moat to entry for competitors put ARM at the top of my watchlist, Brexit or not.

Spending for growth

Pharmaceutical giant Shire (LSE: SHP) is another FTSE 100 company with few ties to the UK as 72% of the company’s 2015 revenue came from the US alone. This is likely to increase in the future after the company recently became the world’s largest provider of treatments for rare diseases by acquiring US firm Baxalta. These drugs often bring in phenomenal margins as little competition leads American insurers to pay top dollar.

Shire achieved this target by spending heavily on both R&D and outside acquisitions. In 2016 alone the $5.9bn deal for Dyax and $32bn tie up with Baxalta went through. These deals have been pricey and Q1 net debt of $6.8bn doesn’t include the Baxalta transaction. But if Shire can improve on that quarter’s 15% year-on-year jump in revenue and 25% net income margin, the company could be one to watch in the future.

Margin marvel

The world’s fourth largest cigarette company Imperial Brands (LSE:IMB) is yet another firm that may be listed in the UK but brings in the vast majority of its revenue overseas. That’s one reason shares are in the green since the Brexit vote, unlike the market at large.

Still, the main reason is that cigarette companies have shown time and time again that their geographic diversification and loyal customers trump increasing government regulation. It doesn’t hurt that Imperial’s adjusted operating margins over the past six months were an astonishing 46.4%. With limited exposure to the UK and considerable foreign earnings to be translated into sterling, Brexit could prove a boon for Imperial Brands in the coming quarters.

The issue with these three firms is that while they're largely immune from Brexit-related problems, their sheer size means their shares are unlikely to double or triple in the coming years. That's why investors looking to juice their portfolio's returns may be better off with smaller firms such as the one the Motley Fool recently named its Top Growth Share.

Shares of this classic British brand have already rocketed 200% in value in the past five years and the Fool's analysts believe they have the potential to triple again in the coming decade.

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