The FTSE 100 posted modest falls on Monday as the oil price topped 100 dollars per barrel once more as the US pressed ahead with a naval blockade of the Strait of Hormuz.

US President Donald Trump announced he would blockade the key shipping route after vice president JD Vance left weekend negotiations with an Iranian delegation in Pakistan without a deal.

The FTSE 100 closed down 17.57 points, 0.2%, at 10,582.96. The FTSE 250 ended down 74.13 points, 0.3%, at 22,276.89, but the AIM All-Share rose 4.83 points, 0.6%, to 782.31.

News of the breakdown in talks between the US and Iran dealt a blow to those hoping for an end to the conflict, sending oil prices higher once more.

The US set a deadline of 2pm on Monday to begin a partial blockade of the Strait of Hormuz, through which a fifth of the world’s oil and gas passes.

“The blockade will be enforced impartially against vessels of all nations entering or departing Iranian ports and coastal areas, including all Iranian ports on the Arabian Gulf and Gulf of Oman,” the US Central Command posted on X.

The threat comes as Tehran has already effectively closed the Strait of Hormuz to oil and other traffic since the start of US-Israel strikes on Iran in late February.

“Reopening the Strait of Hormuz remains the key requirement for reigniting a sustainable rally across risk assets,” said David Morrison, an analyst at Trade Nation.

“Yet there’s also a conviction, rightly or wrongly, that the war will end relatively soon,” he said, noting that oil futures contracts for deliveries later this year are currently priced well below current market prices.

“As far as oil traders are concerned, this war may be in its seventh week, but it should be resolved by summer,” Mr Morrison said.

Brent oil traded higher at 101.95 dollars a barrel on Monday afternoon, up from 96.14 dollars at the time of the equities close in London on Friday.

“Although oil prices have jumped back above the 100 dollars level, the fact that they have not returned to pre-ceasefire highs above 111 dollars per barrel for Brent has tempered the sell-off in risky assets at the start of this week. The peace talks between Iran and the US at the weekend was not a single event, but should be viewed as a process, and there are hopes that more talks will continue,” observed Kathleen Brooks, research director at XTB.

In European equities on Monday, the CAC 40 in Paris closed down 0.3%, as did the DAX 40 in Frankfurt.

In New York, markets were mixed. The Dow Jones Industrial Average was down 0.6%, the S&P 500 was little changed, and the Nasdaq Composite was up 0.3%.

Shares in Goldman Sachs fell 3.6% despite better-than-expected first quarter earnings.

Kicking off a busy week of US banking results, Goldman reported 17.23 billion dollars in total net revenue, up 14% from 15.06 billion dollars the year prior.

But Citigroup analyst Keith Horowitz said an impressive equities performance was offset by a large CET1 capital ratio decline and a weak contribution from its Fixed Income, Currencies & Commodities division.

The yield on the US 10-year Treasury was at 4.33% on Monday, widened from 4.30% on Friday. The yield on the US 30-year Treasury stretched to 4.93% on Monday from 4.90%.

The pound fell to 1.3451 dollars on Monday afternoon from 1.3472 dollars on Friday. Against the euro, sterling rose to 1.1492 euros from 1.1482 euros.

In London, Associated British Foods fell 2.0% as RBC Capital Markets downgraded to ‘underperform’ from ‘sector perform’ seeing further downside risk to consensus earnings forecasts, mainly due to pressure on its largest business, retailer Primark.

On the FTSE 250, Wickes was knocked back 5.1% after a downgrade to ‘hold’ from ‘buy’ by Panmure Liberum which thinks consensus forecasts are too ambitious.

While recruiter Hays fell 2.1% amid the uncertain economic outlook amid the Middle East crisis, and ahead of a trading statement this week.

The US-Iran war weighed on travel operators with budget airlines easyJet and Wizz Air down 2.4% and 5.4%, while cruise operator Carnival lost 2.6% and travel retailer WH Smith declined 3.2%.

Meanwhile, Essentra tumbled 11% as Deutsche Bank downgraded to ‘hold’ from ‘buy’ believing there is a “meaningful risk” that input cost inflation hits demand, particularly in the Europe, Middle East & Africa region.

This would “once again” defer Essentra’s recovery, the bank said.

Elsewhere, Mothercare plunged 21% after reporting lower earnings and sales in financial 2026 amid ongoing Middle East uncertainty.

The Watford-based retailer, which specialises in products for newborn babies and children, said adjusted Ebitda fell to £1.3 million from £3.5 million, while worldwide retail sales by franchise partners declined 22% to £180 million.

Mothercare said the Middle East conflict had an impact of £100,000, citing continued uncertainty for franchise partners in the region. However, it described the recent performance as “usefully resilient” ahead of financial 2027.

Gold traded at 4,714.40 dollars an ounce on Monday, down from 4,775.63 dollars at the same time on Friday.

The biggest risers on the FTSE 100 were Metlen Energy & Metals, up 1.04p at 33.32p, Sage Group, up 23.40p at 841.00p, 3i Group, up 68.50p at 2,759.00p, London Stock Exchange, up 222.00p at 9,190.00p and BAE Systems, up 51.50p at 2,245.50p.

The biggest fallers on the FTSE 100 were United Utilities, down 32.00p at 1,362.00p, Severn Trent, down 71.00p at 3,184.00p, National Grid, down 27.80p at 1,319.80p, Marks & Spencer, down 7.50p at 357.40p and Fresnillo, down 72.00p at 3,524.00p.

Tuesday’s global economic calendar has China trade figures overnight and US producer price inflation data.

Contributed by Alliance News