Shares in temporary power provider Aggreko rocketed after it signed a two-year contract with Energia Argentina and extended another deal in Africa. Aggreko will deliver an extra 150MW of diesel-fuelled power in Argentina and has additionally agreed to extend its existing 300MW of capacity with the same customer about two more years. National Grid's shares were also boosted after they had their neutral rating restated by JPMorgan Chase & Co in a research note issued to investors on Tuesday.After rising initially, Sainsbury's shares took a hit despite a record-breaking Christmas week, where third-quarter like-for-like sales declined only 1.7%, better than the 3.2% fall city analysts had expected. The supermarket group, the first of the major grocers to report after the festive period, warned that it expected the fourth quarter to be "similar to that of our first half", which fell 2.1%. Analysts at Shore Capital reiterated a "sell" rating on the stock.Budget airline Easyjet was also among the fallers despite a 3.2% increase in the number of passengers flown to reach 4,634,977, whilst the company's load factor improved by half a percentage point to reach 88.4%. Resurging oil prices are thought to be responsible, manifesting in increased fuel costs.Associated British Foods also fell after its stock had its 'overweight' rating reaffirmed by JPMorgan Chase & Co in a report issued on Tuesday. Their current price objective of £35.00 points to a potential upside of 13.34% from the company's current price. RisersAggreko (AGK) 1,488.00p +3.48%ARM Holdings (ARM) 976.00p +3.44%United Utilities Group (UU.) 928.50p +3.17%Marks & Spencer Group (MKS) 468.70p +3.15%Standard Chartered (STAN) 971.80p +2.61%BT Group (BT.A) 395.50p +2.49%Prudential (PRU) 1,472.00p +2.47%Diageo (DGE) 1,826.00p +2.47%Ashtead Group (AHT) 1,136.00p +2.43%National Grid (NG.) 916.60p +2.21% FallersMorrison (Wm) Supermarkets (MRW) 169.60p -2.36%Sainsbury (J) (SBRY) 229.60p -2.13%easyJet (EZJ) 1,665.00p -1.01%Associated British Foods (ABF) 3,065.00p -0.74%Coca-Cola HBC AG (CDI) (CCH) 1,138.00p -0.52%SSE (SSE) 1,593.00p -0.44%3i Group (III) 431.50p -0.39%Pearson (PSON) 1,143.00p -0.09%Randgold Resources Ltd. (RRS) 4,755.00p -0.04%