AECOM (ACM) shares tumbled 5.83% in post-market trading on Monday after the infrastructure consulting firm reported fiscal third-quarter results that swung to a loss and slashed its full-year outlook.

The company posted a GAAP operating loss of $75.98 million, a stark reversal from the prior year's profit, as it booked a $337 million pre-tax charge related to a delayed Construction Management project. While revenue of $3.59 billion handily beat analyst expectations of $2.02 billion, adjusted earnings per share came in at a loss of $0.50, missing the consensus estimate of $1.47. The project charge, driven by lower subcontractor productivity, pushed both GAAP and adjusted metrics deep into the red.

Investors also reacted to AECOM's fiscal 2026 guidance, which now calls for adjusted EPS of $3.95 to $4.15—well below the FactSet consensus of $5.96—reflecting the impact of the charge and lower expected net service revenue growth. The disappointing results and outlook overshadowed a 13% increase in total backlog to a record $27.82 billion, triggering the sharp after-hours sell-off.