(ShareCast News) - London markets were muted on Tuesday as investors awaited earnings reports from US tech giants and remained wary of interest rate hikes from the Bank of England and Federal Reserve.As of 15:00 BST, the FTSE 100 was trading flat at 6,784.Royal Mail dipped after delivering a mixed first half trading statement, with group revenues flat as UK parcel volumes were higher than expected across the year but lower letter volumes. Guidance for the full year was kept steady as the three months to 28 June, a period of relative lesser importance compared to the key Christmas season, saw a 2% decline in revenues at the parcel and letter arm UKPIL counterbalanced by 8% growth at European parcels arm GLS.Rolls-Royce reversed Monday's gains, which came as it signed two new deals worth £2.23bn. The company has been selected by SAUDIA, the national carrier of Saudi Arabia to provide long-term TotalCare engine service support worth $1.3bn for Airbus A330 Regional aircraft. It's also been selected by International AirFinance Corporation to provide Trent 700 engines worth $930m for 20 Airbus A330 Regional aircraft.Admiral Group topped the risers after it announced expansion plans to take on 280 extra staff: 130 in its Newport office, 50 in Cardiff and 100 in Swansea. Sector peers Direct Line and RSA Insurance Group were also in favour.Miners Fresnillo and Randgold Resources rebounded from Monday's 'flash crash' in China.Supermarkets Tesco, Sainsbury and Morrison gained, while real estate stocks Barratt Developments and Taylor Wimpey were in the red.