As Americans voted on Tuesday, London's Blue-Chip index slid 1.14%, with investors trimming risk ahead of an unknown overnight outcome and a heavy week of Central Bank and economic news.

While polling stations opened across the United States on Tuesday 3 November 2026, traders in London were heading for the exit. The FTSE 100 closed at 10,638.43, down 122.90 points or 1.14% from Monday's 10,761.33, recording what Reuters described as its steepest one-day fall in a month and ending a four-session winning streak.

The US midterm elections were far from the only Factor behind that decline. Metal prices, bank shares and company results all played prominent roles. But the vote added another layer of uncertainty to a session that was already leaning towards caution, and it offers a useful lens on how global events can shape trading in London even when the outcome is still unknown.

What was at stake in the US

Midterm elections take place halfway through a presidential term. On Tuesday, all 435 seats in the House of Representatives and 35 Senate seats were contested. The composition of Congress can influence spending, taxation and regulation, which is why investors around the world tend to pay attention.

Reuters reported that a Democratic showing was described as already priced in. In market terms, that means investors had largely factored such an outcome into asset prices beforehand, so a result in line with that expectation might have a limited effect. A surprise in either direction could be a different matter.

Why uncertainty encourages caution

When a significant event is due to unfold after the market closes, some investors prefer to reduce their exposure rather than hold positions through a period when they cannot trade. That behaviour can add to selling late in a session, particularly when other worries are already in play.

Tuesday's intraday path fits that pattern. The FTSE 100 was at about 10,705 early on, according to Reuters via MarketScreener, and at roughly 10,687.72 around midday, according to Share Talk, before falling further in the afternoon to its closing level. The deepening of losses as the day wore on suggests caution was building rather than easing.

It is difficult to separate the election's influence from the other forces at work, and no source attributed Tuesday's fall to the vote alone. Still, an overnight event with an unknown result tends to discourage fresh buying, and on a day when sellers already had several reasons to act, that hesitancy among buyers may have made the declines harder to absorb.

The other forces in play

The midterms arrived alongside several other pressures that would have weighed on sentiment regardless.

Metals:The FTSE 350 basic resources index fell 2.6% as copper slid to a multiweek low. Antofagasta (LSE:ANTO) dropped 3.5% and Glencore (LSE:GLEN) fell 2.8%.

Banks:The FTSE 350 banks index lost 1.6% ahead of the Bank of England's decision on Thursday, with HSBC (LSE:HSBA) down 2.0% and the biggest approximate drag on the FTSE 100 in points terms.

Company news:Associated British Foods (LSE:ABF) was among the notable fallers, closing down 2.2% after forecasting lower annual profit, and Coca-Cola Europacific Partners (LSE:CCEP) fell 2.1% after flagging cost pressures.

Oil:Crude slid about 2% in volatile trade after a fall of roughly 7% on Monday, as investors weighed talks aimed at ending the wars in Ukraine and Iran.

Oil was also influenced by a geopolitical development. Early on Tuesday, Brent rose to about $105.25 in Asian trade after The Wall Street Journal, citing US officials, reported a US strike on Iran's Qeshm Island. Tim Waterer, chief market analyst at KCM Trade, said the report "added a degree of risk premium back into the oil price." Iran said contacts with Washington were continuing, though Qatari-mediated talks ended without a breakthrough.

The midterms sit within a packed international calendar. The Bank of England is widely expected to lift Bank Rate by 25 basis points to 4% on Thursday 5 November, which would be the first increase since August 2023. On Friday 6 November, the US October jobs report will offer a fresh reading on the labour market in the world's largest economy, which can influence expectations for US interest rates and the dollar.

For the FTSE 100, US developments matter in several ways. Many constituents earn a significant share of their Revenue abroad, and movements in the dollar can affect the sterling value of those earnings. Sterling traded around $1.3417 on Monday, according to Reuters. Political outcomes in Washington can also shape the outlook for trade, energy and global growth, all of which feed into the fortunes of London's multinational companies.

Not every stock was caught up in the caution. Hiscox (LSE:HSX) rose 2.9% after reporting a 9.5% rise in nine-month premiums, and in the mid-cap FTSE 250, which fell a milder 0.5%, Drax Group jumped 6.6% after unveiling a data centre Partnership with Brookfield Asset Management and Radiant. Those moves show that company-specific news could still outweigh the broader mood.

Key dates to watch

Wednesday 4 November:Eurozone Inflation figures (expected 3.9%) and results from Marks & Spencer, Prudential and others.

Thursday 5 November:Bank of England MPC decision, with a 25bp rise to 4% widely expected.

Friday 6 November:US October jobs report and IAG third-quarter results.

Thursday 12 November:ONS first quarterly GDP estimate for July to September 2026 (7:00am).

The bottom line

US midterm voting day coincided with a risk-shy session for the FTSE 100, which fell 1.14% as metals, banks and company updates weighed. Reuters said a Democratic showing was considered priced in, and results were unknown when London closed, so the election's lasting effect on markets remains to be seen. What is clear is that investors approached the day cautiously, with a rate decision, US jobs data and a wave of corporate results still to come before the week is out.