Shares in transport, logistics and support services group Stobart fell sharply on Thursday morning after the company said that full-year results will miss current market forecasts after a mixed third quarter."Overall, the board expects the group's operating performance for the year to be slightly below current market expectations," Stobart announced.Shares were down 3.02% at 92.18p by 08:30.The Transport & Distribution division, which accounted for the majority of profits in the first half, is said to be performing in an "uncertain economic environment". Within this unit, the firm has decided to close down its Chilled operation following a restructure review due to challenging conditions.Its well-known brand, Eddie Stobart, is now in the traditionally quieter months of January and February, so the group said that this period is focused on cost control to reduce risk in the final quarter.Elsewhere, the loss-making Air division has incurred extra costs in the initial start-up phases after the group invested heavily in training and service delivery to meet faster-than-expected initial growth.The Biomass division has had its growth delayed by the timing of UK government legislation but is said to be performing well.Meanwhile, Stobart Estates, as reported in the interim results, has seen slower-than-forecast growth "due to current market conditions". The group said that the outturn for this division will depend on the timing of disposals and valuations."The board continues to focus on realising value from all investments in the short and medium term, whilst managing the business in the delivery of trading results in the current uncertain economic environment," the group said.