Footsie is slightly lower in early dealings, with the advertising group WPP the leading share index's heaviest faller after reporting interim results.WPP said half-year results continue to reflect the impact of the global economic contraction, which continued to intensify in the second quarter, though results for July did indicate a 'less-worse' picture. Pre-tax profit for the six months fell 47% to £179.3m, reflecting the impact of higher sterling translation of interest costs on Euro-denominated debt. Pre-tax profits plunged at Tullow in the first half of the year as the firm felt the pinch of the slide in oil prices. The oil company posted a pre-tax profit of £34.8m in the six months to June 30, down by 83% from the £126m reported the previous year. Revenues slid 23% to £291.3m from £378m. It was a similar story at mining firm Antofagasta which posted a sharp slide in pre-tax profits as metals prices slid. For the six months to June 30, pre-tax profits totalled $476.6m, compared with $1.66bn over the same period the previous year, as revenues slid to $1.18bn from $2.40bn. Outsourcing specialist Serco is the top riser after it said its strong performance in the first half and the good start to the second period supports its expectation in achieving its financial guidance for 2009 and beyond. Pre-tax profit for the half-year increased 32.8% to £93.4m on revenue that rose to £1,950 from £1,491m. The strong results allowed the firm to hike dividends by 25% to 1.85p per share. Lovell, the affordable housing division of construction and regeneration specialist Morgan Sindall, has been chosen as a contractor for a major redevelopment programme in Hampshire. The £20m project will involve the demolition of 100 bungalows built in the sixties, and the construction of 189 energy-efficient new homes. Yet Morgan is the mid-cap index's heaviest faller. Meanwhile, support services and construction company Carillion has won three new contracts worth £121m. The company has been chosen by real estate investment trust Segro for a £50m project in Farnborough that will involve the construction of four office buildings in Farnborough.Oil services group John Wood saw profits slide in the half-year as the tough market conditions hit exploration and production (E&P) spending worldwide. The group said the recent higher oil prices are likely to have little impact on E&P spending in the second half.Ireland's largest bookmaker Paddy Power reported a decline in half year pre-tax profit but saw 20% growth in online customers.