A report of US military action near the Strait of Hormuz briefly lifted crude on Tuesday, a reminder of how closely parts of London's Blue-Chip index are tied to the oil price.

In the early hours of Tuesday 3 November 2026, during Asian trading, Brent Crude edged up to around $105.25 a barrel. The trigger was a report in The Wall Street Journal, citing US officials, that the United States had struck Iran's Qeshm Island. According to those officials, the strikes were defensive, intended to stop Iran attacking commercial vessels in the Strait of Hormuz.

The bounce followed a dramatic slide the day before. On Monday 2 November, Brent settled at $104.77, down $8.66 or 7.63%, while US benchmark WTI settled at $96.46, down $7.66 or 7.36%. For the FTSE 100, which counts large energy producers, airlines and energy-intensive businesses among its members, these swings are more than background noise.

Why Qeshm and Hormuz matter

Qeshm Island sits in the Strait of Hormuz, a narrow passage linking the Gulf with the open ocean. Before the current conflict began in late February 2026, roughly one-fifth of the world's Crude Oil and Natural Gas shipments passed through it. Any threat to that route, real or perceived, tends to feed directly into prices.

Tim Waterer, chief market analyst at KCM Trade, summed up the immediate reaction, saying the report "added a degree of risk premium back into the oil price." A risk premium, in this context, is the extra amount traders are willing to pay for oil because of the possibility that Supply could be disrupted. It can build quickly on alarming headlines and fade just as fast when tensions appear to ease.

Diplomacy has also been moving prices. Iran said contacts with Washington were continuing, although talks mediated by Qatar ended without a breakthrough. Reuters reported that crude slid about 2% on Tuesday in volatile trade, after a fall of roughly 7% on Monday, as investors weighed talks aimed at ending the wars in Ukraine and Iran. The early lift from the Qeshm report, in other words, did not hold through the session.

Mapping the FTSE 100's oil sensitivity

The FTSE 100's relationship with oil runs in more than one direction, which is part of what makes it distinctive among major indices.

Producers:Integrated energy groups such as Shell (LSE:SHEL) and BP (LSE:BP.) are among the index's best-known members. In general terms, higher crude prices can support the revenues and cash flows of oil producers, while sharp falls can weigh on them.

Heavy fuel users:Airlines, including International Airlines Group (LSE:IAG), are typically exposed to fuel costs, which can be one of their largest expenses. Rising oil can squeeze margins unless hedged or passed on through fares. IAG's third-quarter results on Friday 6 November may shed light on how the group is handling this environment.

Consumer and industrial businesses:Companies that rely on energy for manufacturing, transport or packaging can see costs climb when oil and gas prices are elevated.

That last group was in focus on Tuesday. Coca-Cola Europacific Partners (LSE:CCEP) fell 2.1% after flagging cost pressures. Chief executive Damian Gammell said that "the geopolitical situation has impacted operating costs." Associated British Foods (LSE:ABF), which fell 2.2% after forecasting lower annual profit, cited higher gas costs among the reasons its Sugar Business swung to a £47m loss, and said its expected Sugar loss for the next financial year depends partly on gas costs.

Insurers can feel the conflict too, though through a different route. Hiscox (LSE:HSX), which rose 2.9% on Tuesday, reported marine losses linked to the Middle East conflict, more than offset by a benign period for natural catastrophes.

The rate connection

Oil's influence on the FTSE 100 also travels through interest rates. Reuters noted that elevated oil prices have fuelled Inflation fears and that many central banks have raised rates. The Bank of England is widely expected to lift Bank Rate by 25 basis points to 4% on Thursday 5 November, which would be its first rise since August 2023. ING argued that the worsening energy crisis had "made it much harder for the Bank not to act."

That creates a chain reaction. A geopolitical headline can lift oil; higher oil can intensify inflation concerns; those concerns can push up rate expectations; and higher expected rates can weigh on share valuations across the index. Money markets had fully priced four 25bp hikes by next September, according to LSEG data cited by Reuters, which shows how strongly the energy shock is shaping the outlook.

Despite the early oil bounce, the broader market had a difficult day. The FTSE 100 closed at 10,638.43, down 122.90 points or 1.14%, its steepest one-day fall in a month according to Reuters. Mining shares led the declines as copper fell to a multiweek low, with the FTSE 350 basic resources index down 2.6%. Banks also weakened ahead of the rate decision, and HSBC (LSE:HSBA) fell 2.0%.

Not every energy-related move was negative. In the mid-cap space, Drax Group, a FTSE 250 stock rather than a FTSE 100 member, rose 6.6% after announcing a data centre Partnership with Brookfield Asset Management and Radiant. That move was company-specific rather than a reaction to crude prices, but it underlined how varied the energy theme has become.

The US midterm elections, held on Tuesday 3 November, added another layer of uncertainty. Reuters described a Democratic showing as priced in;

Key dates to watch

Wednesday 4 November:Eurozone inflation figures, expected at 3.9%.

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

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

Thursday 12 November:ONS first quarterly GDP estimate for July to September 2026.

The bottom line

The reported US strike on Qeshm Island showed how quickly a single headline can reinsert a risk premium into crude, even if Tuesday's early bounce faded as the session wore on. For the FTSE 100, oil exposure cuts several ways: it can help producers, hurt fuel-hungry airlines and squeeze consumer businesses, while also shaping the Interest Rate outlook. With the Strait of Hormuz still central to global energy flows and diplomacy unresolved, crude is likely to remain one of the key variables for London's blue chips in the weeks ahead.