BP is lower after it announced the $680m (£421m) acquisition of a Brazilian ethanol producer.BP has moved to improve its green credentials with the purchase of Companhia Nacional de Açúcar e Álcool (CNAA). The acquisition is the oil giant's biggest ever in the alternative energy sector.Insurer Prudential is lower because of conerns about the Japanese earthquake. African Barrack Gold, which is being demoted from the FTSE 100 index is lower today. Supermarket group Morrison is still rising after yesterday's results, while Tullow Oil and Aggreko have clawed back some of their losses after their results announcements. FTSE 100 - Risers ARM Holdings (ARM) 532.00p +1.82%Tullow Oil (TLW) 1,370.00p +1.41%BG Group (BG.) 1,437.00p +1.27%WPP (WPP) 785.00p +1.09%Rio Tinto (RIO) 3,972.00p +1.03%Morrison (Wm) Supermarkets (MRW) 287.90p +1.02%Compass Group (CPG) 543.00p +1.02%Cairn Energy (CNE) 426.40p +0.78%Inmarsat (ISAT) 596.50p +0.76%Aggreko (AGK) 1,400.00p +0.72%FTSE 100 - Fallers Experian (EXPN) 740.50p -3.08%Essar Energy (ESSR) 492.60p -2.26%Admiral Group (ADM) 1,588.00p -2.10%Autonomy Corporation (AU.) 1,596.00p -1.85%Prudential (PRU) 722.00p -1.77%BP (BP.) 468.20p -1.74%Schroders (Non-Voting) (SDRC) 1,364.00p -1.59%African Barrick Gold (ABG) 509.50p -1.55%Capita Group (CPI) 768.50p -1.54%Smiths Group (SMIN) 1,306.00p -1.51%