London is struggling to hold onto its bright start despite a good morning for shares in beleaguered oil giant BP.BP said the cost of the clean-up in the Gulf of Mexico has risen to $3.5bn from $3.12bn a week ago and $2.65bn at the end of June, although some say that figure could eventually hit $70bn. The first half of August remains the current estimate of the most likely date by which the first relief well will be completed and kill operations performed, the company said.But press coverage suggesting both Exxon Mobil and Chevron have received White House approval to launch a bid for BP has got the market excited. Royal Dutch Shell is up in sympathy.Falkland Oil and Gas shares crashed as it failed to find any oil in the East Falkland basin after its first exploration well in the region, Toroa F61/5-1, turned up dry. "The well did not encounter any reservoired hydrocarbons and will now be plugged and abandoned," said the AIM-listed company, a favourite with small investors.Banks are off the pace. Confirmation that JC Flowers is to use building society Kent Reliance to launch an assault on the UK retail bank market could mean the space getting very crowded soon. Lloyds, Barclays and Royal Bank of Scotland are all lower.Rio Tinto has referred Canadian miner Ivanhoe's breaches of a private placement agreement to arbitration following its adoption of the shareholders rights plan. The mining heavyweight, which recently increased its stake in Ivanhoe to 29.6%, has warned Ivanhoe before it adopted the plan would breach Rio Tinto's contractual rights. Other miners are lower led by Kazakhmys and Vedanta.Oil industry services giant Petrofac has won its first production enhancement services contract in Romania after tying up a deal with Petrom, which owns the Ticleni oilfield and its eight satellite fields. Thomas Cook has agreed to buy Öger Tours, a well-known German tour operator specialising in package holidays to Turkey, from its founding shareholder Vural Öger for about €30m. The consideration will be paid in cash.Meanwhile, strong online sales and a boost from the World Cup helped pizza delivery firm Domino's post another bumper set of results. Profits jumped 30% to £17m, from £13.1m, in the half year. That's ahead of consensus of £16.5m. Sales for the 26 weeks ended 27 June 2010 grew by 20.8% to £237.1m (2009: £196.4m).