Shares in National Express have come crashing down after the consortium stalking the rail and bus firm dropped its interest in making a bid for the bus and train group, which is now considering a sizeable rights issue to help repair its balance sheet.Fellow transport group Stagecoach is lower in sympathy.Things are going swimmingly for Salamander Energy as the Asia-focused oil and gas group enjoys the rise in the crude price. Engineering project designer Aveva is a top riser after saying its latest six month period has seen trading slightly ahead of expectations helped by exchange rate movements and solid demand from its existing customers.FTSE 250 - RisersSalamander Energy (SMDR) 273.60p +9.22%Lamprell (LAM) 213.70p +5.79%Paragon Group Of Companies (PAG) 168.70p +4.78%Imagination Technologies (IMG) 206.90p +4.44%AG Barr (BAG) 882.00p +4.13%Aveva Group (AVV) 1,011.00p +3.69%Moneysupermarket.com (MONY) 83.60p +3.53%Rathbone Brothers (RAT) 960.00p +3.23%SThree (STHR) 271.20p +2.88%Robert Wiseman (RWD) 466.90p +2.86%FTSE 250 - FallersNational Express Group (NEX) 354.80p -24.67%Laird (LRD) 207.90p -5.20%Stagecoach Group (SGC) 155.90p -5.11%DS Smith (SMDS) 120.70p -4.58%Aberdeen Asset Management (ADN) 138.70p -4.01%Gem Diamonds (GEMD) 248.90p -3.83%Regus (RGU) 114.90p -3.69%Petropavlovsk (POG) 1,102.00p -3.33%JPMorgan Japanese Inv Trust (JFJ) 150.30p -3.28%Millennium & Copthorne Hotels (MLC) 367.60p -2.98%