Spirax led the index lower after the company opted to maintain its existing annual forecast, disappointing shareholders despite reporting improved first-half results. The insurance sector faced separate pressures, with Legal & General shares sliding 3.1% following rating cuts from both UBS and Goldman Sachs. Analysts at UBS cited concerns over peak valuations, thinning margins in the firm's pension risk transfer business, and a declining solvency ratio. The broader FTSE 350 insurers index finished the day 2.5% lower, dragging down rivals including Standard Life and Prudential.

Energy stocks provided a rare counterweight to the market's decline. Oil prices climbed following reports that diplomatic negotiations regarding the Strait of Hormuz had reached an impasse, boosting shares in BP and Shell by 1.8% and 2.2% respectively. Meanwhile, mid-cap stocks saw their own volatility, with Genuit dropping 5.6% after reporting that wet weather and regional conflict hindered earnings. Investors now look toward Wednesday’s U.S. inflation data and Thursday’s UK GDP figures to clarify the trajectory of future monetary policy.