FTSE 100 ends flat on US tariff uncertainty

Feb 23 (Reuters) - The UK's FTSE 100 ended flat on Monday as uncertainty over U.S. trade policy largely stymied trade, although Johnson Matthey slumped after the chemical company accepted a cut to the sale price of its catalyst unit to Honeywell.

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

U.S. President Donald Trump at the weekend said he would implement a new 15% tariff on global imports, following the U.S. 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% after reaching a deal with the U.S. last year, but Trump's promise to reimpose higher levies at 15% means businesses may face higher duties.

MONDI AND JOHNSON MATTHEY BOTH FALL

Britain does not expect the new tariffs to impact the "majority" of a UK-U.S. economic deal, Prime Minister Keir Starmer's spokesperson said.

Tariff concerns weighed on packaging and paper group Mondi MNDI.L, which lost 4.3%, while its U.S. peers also fell.

Johnson Matthey JMAT.L slumped 16.4% to the bottom of the mid-cap index, after it agreed to lower the sale price of its catalyst technologies business to Honeywell HON.O following the unit's underperformance in fiscal 2025.

British aerospace and defence stocks .FTNMX502010 pulled back after touching a record high on Friday.

Rolls-Royce Holdings RR.L dipped 0.2% despite a media report that said the engine maker is expected to launch a share buyback worth as much as 1.5 billion pounds ($2 billion) alongside its annual results this week.

Meanwhile, precious-metal miners .FTNMX551030 rose 5.2% to a record high after gold climbed to a three-week high as investors sought safe-haven assets. GOL/