Spirax shares slide 10% despite strong first-half growth as investors seek more Proactive uses images sourced from ShutterstockSpirax Group PLC (LSE:SPX) saw shares fall 10% on Tuesday despite delivering a solid set of first-half results, as investors were left wanting more after the company held its full-year guidance steady rather than upgrading it. The steam engineering specialist reported group revenue up 5% to £863.8 million for the six months to 30 June, comfortably ahead of its own internal plan of 1.5% growth. Statutory operating profit jumped 44% to £154.2 million, with margin up 490 basis points to 17.9%, boosted by the comparison against one-off restructuring costs taken in 2025. On an adjusted basis, operating profit rose 8% to £171.1 million, with margin up 50 basis points to 19.8%. The board reiterated full-year guidance of mid-single-digit organic revenue growth and organic margin progress.