The shares fell 16p to 224p after a statement from Sir Keith Stuart, the chairman, prompted downgradings among stockbroking analysts.
Sir Keith said: 'Based on revenues in July and August, our ports and transport business is unlikely to produce better results in the second half of the year than those in the first six months.'
Sir Keith confirmed a provision of pounds 10m on ABP's development property portfolio for the six months to 30 June. The provision was first announced last July and reduces the total value of the development property portfolio to pounds 124m.
'Whether we need to make any further provisions at the end of the year will depend on the situation then,' Sir Keith said.
At present some 200,000 sq ft of the 288,100 sq ft of development property in the South-east is vacant. The company does not expect any significant property sales in the next few months.
The property provisions hit first-half pre-tax profits, which fell to pounds 15.1m from pounds 31.7m last year. Turnover dropped from pounds 197.1m to pounds 108.1m. In 1991 turnover was boosted by the pounds 75.2m sale of Aldwych House, a development property.
Total tonnage handled at the ports in the first half rose by 1.4 million tonnes to 53 million tonnes. A reduction in volumes of construction materials and motor vehicles was offset by an increase in bulk trades like wheat and coal.
The port and transport division's profits fell to pounds 37.6m from pounds 39.6m after redundancy payments of pounds 2m. Property investment profits rose from pounds 10.1m to pounds 11.2m as rents were revised.
Earnings per share fell to 5.7p from 12.0p. The interim dividend is being lifted to 3.25p from 3.1p.Reuse content