Oil explorer JKX Oil saw the lower oil prices crimp profits for the half-year but said its second half performance is expected to be in line with expectations. Pre-tax profit slumped to £44.6m from £83.5m before revenues fell to $78.5m versus $116.8m in the same period last year. Revenues were weighed by oil revenues sliding 67%, slightly offset by gas prices rising 23%. The group said current oil production exceeds 13,000 boepd, an increase of around 30%.Interim dividend has been raised 5% to 2.3p per share.Fellow oil and gas firm Melrose Resources upgraded its full year production guidance but saw half-year results also hit by lower commodity prices.The group said production levels from its existing fields and new Egyptian developments have been ahead of expectations, allowing it to increase 2009 production guidance to 37.5 Mboepd working interest basis (16.3 Mboepd net entitlement).But with average commodity sale prices pre-tax profits fell to $19.7m from $134.1m previously on revenue that fell to $97.6m against $234m. Investment company SVG Capital reported an 18% drop in net asset value to 171 pence in the six months to 30 June but said its underlying portfolio performance is stabilising.Investment bank Evolution saw adjusted operating profit jump 102% in the half year ended 30 June to £9.1m as Investment Banking income rose 93% to £33.9m, mainly from more sustainable secondary equities and fixed income commissions.