Mid caps were on the up on Tuesday, as weakness in the industrial metals sector was eclipsed by strength in oil, telecommunications and engineering stocks.As of 15:15 BST, the FTSE 250 was trading 0.6% higher at 18,010.Ladbrokes shares jumped after the bookie chain confirmed it was in merger talks with the board of Gala Coral. The tie-up would create the UK's largest bookmaker with over 4,000 betting shops nationwide.Telecom Plus was trading higher after confirming its trading was in line with expectations, thanks to an increase in pre-tax profits. "Looking forward we are confident that we will deliver record revenues, profits, and earnings per share for the current year," said group chief executive Andrew Lindsay.Oilfield services outfit Petrofac gained after saying that additional costs tied to the development of its flagship project in the Shetland Islands would be partially offset by tax provisions. Charles Stanley upgraded the stock to 'accumulate', saying there is "hope that Petrofac will turn a corner".Designer shoe retailer Jimmy Choo dipped on reports that founder Tamara Mellon could launch a legal battle against the firm, on grounds of anti-competitive behaviour, damaging her new label, Tamara Mellon Brand.Miners Evraz and Lonmin extended losses as three-month delivery contracts for metals fell across the board on concerns over demand in China and Europe. RisersLadbrokes (LAD) 138.10p +13.10%Serco Group (SRP) 132.90p +7.61%Petrofac Ltd. (PFC) 924.00p +6.27%RPC Group (RPC) 684.50p +4.42%Telecom Plus (TEP) 851.50p +3.71%Entertainment One Limited (ETO) 354.00p +3.54%Hunting (HTG) 644.50p +3.37%Ocado Group (OCDO) 407.90p +3.29%Greene King (GNK) 858.50p +2.81%Workspace Group (WKP) 898.00p +2.69%FallersEvraz (EVR) 139.60p -4.90%Lonmin (LMI) 125.90p -2.40%Mitchells & Butlers (MAB) 464.70p -2.23%Jimmy Choo (CHOO) 158.40p -2.22%Foxtons Group (FOXT) 257.10p -2.02%Polymetal International (POLY) 539.50p -1.91%Crest Nicholson Holdings (CRST) 571.00p -1.81%Synergy Health (SYR) 1,745.00p -1.69%Just Retirement Group (JRG) 178.00p -1.66%Woodford Patient Capital Trust (WPCT) 114.00p -1.64%