The bus and rail operator said pretax profit fell 18 percent to £88.7m.
Sales in the six months to end-October rose 14 percent to £1.29bn, also below estimates of 1.37 billion pounds.
The results were hurt by a weak performance at the company's UK Rail division, which swung to an operating loss of £6.9m from a profit of £22.9m.
"This was due to losses incurred at East Midlands Trains where revenue remains below the level forecast when the contract was originally awarded," Stagecoach said.
However, the company expects a stronger second-half, with East Midlands seen returning to profitability.