FTSE 100 closes flat amid US tariff uncertainty

The blue-chip index ended 0.02 per cent lower after closing at record highs last week

The UK’s FTSE 100 ended flat on Monday as uncertainty over U.S. trade policy largely stymied trade, although Johnson Matthey plunged after the chemical company accepted a cut to the sale price of its catalyst unit to Honeywell.

The blue-chip index ended 0.02 per cent lower after closing at record highs last week. The domestically focused mid-cap FTSE 250 was down 0.9 per cent.

U.S. President at the weekend said he would implement a new 15 per cent tariff on global imports, following the Supreme Court’s decision on Friday to strike down his emergency-based tariffs.

The British government had negotiated a lower reciprocal tariff rate at 10 per cent after reaching a deal with the U.S. last year, but Trump’s promise to reimpose higher levies at 15 per cent means businesses may face higher duties.

Britain does not expect the new tariffs to impact the “majority” of a UK-U.S. economic deal, U.K. prime minister’s spokesperson said.

Tariff concerns weighed on packaging and paper group Mondi, which shed 4.3 per cent, while its U.S. peers also dropped.

Johnson Matthey plunged 16.4 per cent to the bottom of the mid-cap index, after it agreed to lower the sale price of its catalyst technologies business to Honeywell following the unit’s underperformance in fiscal 2025.

British aerospace and defence stocks pulled back after hitting a record high on Friday.

Rolls-Royce Holdings slipped 0.2 per cent despite a media report that said the engine maker is expected to launch a share buyback worth as much as 1.5 billion pounds alongside its annual results this week.