Heritage Oil is the best performer on the FTSE 100 Tuesday after the oil explorer announced that it is buying back $100m (£60m) in shares, because its "considers that the current share price is trading at a significant discount to the intrinsic, underlying value of the company."Micro Focus International saw shares rockets after it confirmed speculation of a potential sale. The software firm revealed that it has received a "very preliminary, non-binding approach in relation to a possible offer" and is said to be considering its response.Bookmaker William Hill is higher after RBS upped its target price following a positive first quarter update.Printing technologies firm Domino Printing Sciences is wanted after forming a joint venture with food safety specialist New Market Impressions to develop and deploy proprietary food safety and traceability technologies for the US egg industry, with plans to expand globally. Meanwhile, shares in silver and gold miner Hochschild Mining took a hit after the group said that production at its main mine has stopped due to a strike. Miners Centamin Egypt and Kenmare Resources were also lower.FTSE 250 - RisersHeritage Oil (HOIL) 262.90p +7.61%Micro Focus International Plc (MCRO) 361.80p +7.04%Pace (PIC) 162.00p +4.38%Brewin Dolphin Holdings (BRW) 169.10p +3.87%William Hill (WMH) 220.50p +3.38%CPP Group (CPP) 126.00p +2.77%Domino Printing Sciences (DNO) 625.00p +2.63%Rank Group (RNK) 152.80p +2.55%Cookson Group (CKSN) 695.50p +2.51%RPC Group (RPC) 334.00p +2.49%FTSE 250 - FallersCentamin Egypt Ltd. (CEY) 135.50p -4.04%Mothercare (MTC) 407.80p -3.96%Kenmare Resources (KMR) 47.00p -3.51%Bwin.party Digital Entertainment (BPTY) 158.40p -3.36%Imagination Technologies Group (IMG) 482.10p -2.55%Inchcape (INCH) 357.00p -2.35%Telecity Group (TCY) 518.00p -2.26%Hochschild Mining (HOC) 616.00p -2.22%Salamander Energy (SMDR) 296.80p -1.98%JKX Oil & Gas (JKX) 303.00p -1.94%FTSE TechMARK - RisersE2V Technologies (E2V) 132.25p +5.17%NCC Group (NCC) 599.50p +3.94%Oxford Biomedica (OXB) 5.70p +3.64%Antisoma (ASM) 2.49p +3.53%Torotrak (TRK) 45.50p +3.41%AEA Technology Group (AAT) 4.60p +2.79%Phoenix IT Group (PNX) 215.00p +2.20%Vectura Group (VEC) 65.00p +1.56%Sinclair Pharma (SPH) 34.75p +1.46%Ricardo (RCDO) 374.00p +1.29%FTSE TechMARK - FallersSkyepharma (SKP) 35.00p -4.11%Alterian (ALN) 112.25p -2.39%Anite (AIE) 62.25p -2.35%XP Power Ltd. (DI) (XPP) 1,618.00p -1.94%Sepura (SEPU) 47.00p -1.83%Wolfson Microelectronics (WLF) 215.25p -1.82%Emblaze Ltd. (BLZ) 58.50p -1.68%Promethean World (PRW) 66.00p -1.49%Innovation Group (TIG) 17.00p -1.45%Vislink (VLK) 19.00p -1.30%