With Brexit being a distinct possibility, many investors may be feeling nervous about the prospects for a number of their holdings. Clearly, the UK leaving the EU could cause share prices to fall in the short run as investors view the outlook for the UK, Europe and the rest of the world with greater uncertainty. However, some companies may be worse affected than others.

One such stock is BT (LSE: BT-A). Although Brexit may or may not be bad news for the UK economy over the medium-to-long term, it’s likely to cause investor sentiment in UK-focused stocks such as BT to come under greater pressure than is the case for their international index peers. That’s simply because the UK leaving the EU is an unprecedented event that could hurt (or benefit) future economic growth.

However, the risk of hurt is likely to be enough to send BT’s shares downwards. Furthermore, BT has a relatively high level of debt on its balance sheet and if interest rates rise in response to higher levels of inflation caused by a weaker pound making imports more expensive, BT’s debt servicing costs may increase and cause profitability to come under further strain. And with BT having just purchased EE and seeking to expand rapidly, its relatively risky strategy could cause investors to become less optimistic about the company’s capital gain potential in a more risk-off environment.

Appealing buy

With Rolls-Royce (LSE: RR) being a truly international engineering company, its shares are unlikely to be hit particularly hard by Brexit. After all, it supplies jet engines to the global aviation industry and is a major player in the defence sector, so what happens in the near term in the UK is arguably less important to it than the outlook for the US and global economy.

Furthermore, Rolls-Royce trades on a wide margin of safety at the present time, which should lessen the scope for a share price fall. For example, it has a price-to-earnings growth (PEG) ratio of just 0.6 and this indicates that it offers excellent long-term capital gain potential. Furthermore, with Rolls-Royce being a possible bid target, it continues to be a relatively appealing buy whether the UK leaves the EU or not.

Defensive giant

Meanwhile, National Grid (LSE: NG) remains one of the most defensive stocks on the FTSE 100, so is unlikely to fall by more than the wider index if the UK decides to leave the EU today. Certainly, there are question marks surrounding the company’s long term future, with it being argued recently that National Grid should be broken up. However, it remains a top-notch income play that should offer a less volatile shareholder experience thanks to its beta standing at 0.5.

With National Grid’s yield currently being 4.5%, it offers a high level of income that could be used to reinvest in other stocks at potentially lower levels should Brexit occur and cause the stock market to fall. And with National Grid’s business model being relatively robust and its dividend covered 1.4 times by profit, a healthy level of dividend growth is on the cards, which could still beat inflation even if Brexit occurs and the price level rises.

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Peter Stephens owns shares of National Grid. 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.