Election day in the US is finally here, and the outcome remains on a knife-edge. The results of the Trump-Harris Presidential runoff could have significant short- and long-term consequences, including for UK shares and stocks around the globe.

Here are two FTSE 100 shares that might rise in value if Donald Trump returns to the White House.

BAE Systems

Defence businesses like BAE Systems (LSE:BA.) have surged in value since Russia’s 2022 invasion of Ukraine. Arms demand has risen as Western nations restock their arsenals following the end of the Cold War. It’s a trend that’s widely tipped to continue as geopolitical tensions ramp up.

Defence sector sales could receive an extra shot in the arm if Trump succeeds today, too. Military improvement is one of his stated priorities, including building an ‘Iron Dome’ missile defence system and implementing widescale modernisation.

This could create a windfall for BAE Systems considering its top-tier supplier status to the US. Last year, the firm generated 42% of its revenues from there, making it the company’s single largest market.

But this is not all. A Trump Presidency could also have significant implications for other countries’ defence spending.

Criticising NATO countries for not meeting spending obligations was a hallmark of his last stint as President. And rumours circulate that he’ll demand the defence bloc hike arms-related expenditure to 3% of gross domestic product (GDP) if he wins today, up from 2% at present.

Defence businesses like BAE still face threats like supply chain issues and cost inflation. But, on balance, I think the FTSE company looks in great shape.

Shell

If his last stint in the White House is any guide, the oil industry could also be a big beneficiary of a Trump election win. Investing in Shell (LSE:SHEL) could be a good play on this theme.

Between 2016 and 2020, the former President introduced a broad spectrum of measures that boosted fossil fuel producers. He increased the number of drilling leases on federal lands, approved pipeline projects such as Keystone XL, and dialled back environmental legislation to help businesses cut costs.

Trump’s support for the oil sector hasn’t wavered in the intervening years either. On the campaign trail he’s pledged to increase production as part of his ‘America First’ policy.

Shell might be one of the big winners if Trump wins today. It’s one of the world’s biggest oil and gas producers, with operations in 70 countries. And it sources a substantial amount of earnings from the US thanks to its extensive refining operations and upstream assets.

That said, there will still be risks to investing in oil companies, whoever secures the election. The oil market faces a large oversupply as China’s economy cools and new capacity comes on stream. This could keep oil prices on their recent downward path, hitting producers’ revenues.

What’s more, countries are heavily investing in renewable energy to wean themselves off oil and gas, which poses a long-term problem. Though Shell’s own investment in renewables could help limit this danger.