FTSE 100 peers Rolls-Royce and BAE systems lifted the aerospace and defence sector to the top of the pile on Thursday afternoon.Power systems giant Rolls-Royce was gaining 4% today, helped by Morgan Stanley which reiterated its overweight rating on the stock today. Investors may be building positions before next Wednesday when the stock goes ex-dividend - from that date on, those who invest will not have the right to the group's latest dividend.Meanwhile defence group BAE Systems was edging higher, rebounding after yesterday's slight fall when it was reported that 2,000 workers at its Samlesbury and Warton sites would take one day of unpaid leave a month for two years in order to prevent compulsory redundancies. Top performing sectors so far todayAerospace and Defence 3,724.17 +2.15%Electronic & Electrical Equipment 3,501.42 +1.86%Industrial Engineering 7,921.67 +1.83%Mobile Telecommunications 3,997.71 +1.70%Chemicals 8,645.19 +1.24%Bottom performing sectors so far todayElectricity 8,402.18 -1.44%Construction & Materials 3,415.11 -0.83%Health Care Equipment & Services 3,441.09 -0.81%Fixed Line Telecommunications 2,453.92 -0.79%Industrial Metals & Mining 3,959.14 -0.64%BC