The share price of FTSE 250 upstream exploration and production firm Heritage Oil surged on Wednesday after the company said that production at its OML 30 licence in Nigeria is back at normal levels.Output has now returned to rates of over 35,000 barrels of oil per day (bopd) after falling to just 6,932 bopd in the first quarter as flow stations had to be shut down due to employee strikes. The company said that a number of "temporary factors" that had caused lower-than-expected production have now been "successfully addressed".Price-comparison website Moneysupermarket.com was sharply lower given that today is the ex-dividend date for its special interim dividend of 12.92p a share announced last week as it returns £70 to shareholders.LondonMetric Property, Booker and Intermediate Capital were also in the red after going ex-dividend today.Lighting, signalling and electronics group Dialight was rebounding after posting heavy falls the day before. The company said on Tuesday that first-half profits would be adversely affected by weaker sales in the Signal segment and additional costs from the planned extra sales in the Lighting segment. FTSE 250 - RisersHeritage Oil (HOIL) 144.00p +5.73%New World Resources A Shares (NWR) 99.75p +5.56%National Express Group (NEX) 215.20p +4.36%Dialight (DIA) 1,201.00p +3.80%Hays (HAS) 87.00p +3.69%BTG (BTG) 375.00p +3.28%Keller Group (KLR) 950.50p +2.76%Dixons Retail (DXNS) 42.25p +2.57%TalkTalk Telecom Group (TALK) 227.40p +2.39%Mitie Group (MTO) 253.90p +2.38%FTSE 250 - FallersMoneysupermarket.com Group (MONY) 185.80p -6.40%Oxford Instruments (OXIG) 1,372.00p -5.70%Imagination Technologies Group (IMG) 301.00p -5.32%Hochschild Mining (HOC) 209.30p -3.86%LondonMetric Property (LMP) 109.90p -3.26%Utilico Emerging Markets Ltd (DI) (UEM) 175.00p -2.51%Cairn Energy (CNE) 255.10p -2.37%Hunting (HTG) 782.00p -2.37%Electrocomponents (ECM) 247.30p -2.33%BH Macro Ltd. USD Shares (BHMU) 20.76 -2.31%