Trading systems developer Fidessa gained experiencing a 'marked and positive change of sentiment in the market' in recent months. Ocado extended Friday's gains which came on the back of Exan BNP's decision to raise its target price on the stock from 140p to 145p. Third-quarter power generation at Essar Energy almost doubled, causing shares to rise today. Power generation rose 93% to 2,862m units compared to 1,481m units in the same quarter a year earlier.Telecity Group shares took a hit ahead of its full year update due Wednesday. FTSE 250 - RisersOcado Group (OCDO) 125.90p +6.33%Petra Diamonds Ltd.(DI) (PDL) 119.40p +5.95%Fidessa Group (FDSA) 1,580.00p +3.47%Man Group (EMG) 100.90p +3.06%Essar Energy (ESSR) 145.00p +2.84%UK Commercial Property Trust (UKCM) 69.95p +2.34%Ophir Energy (OPHR) 488.00p +2.31%New World Resources A Shares (NWR) 281.00p +2.11%Aegis Group (AGS) 238.40p +1.75%Diploma (DPLM) 587.00p +1.73%FTSE 250 - FallersTelecity Group (TCY) 824.00p -4.63%Taylor Wimpey (TW.) 73.00p -2.86%Menzies(John) (MNZS) 735.00p -2.65%Brewin Dolphin Holdings (BRW) 204.00p -2.58%Bovis Homes Group (BVS) 627.00p -2.34%Barratt Developments (BDEV) 220.80p -2.34%Salamander Energy (SMDR) 197.30p -2.33%Berkeley Group Holdings (The) (BKG) 1,787.00p -2.30%Debenhams (DEB) 97.15p -2.26%Anite (AIE) 155.80p -2.26%NR