NMC Health continued to surge, extending Friday's gains after its Chief Executive Officer and founder, B. R. Shetty, purchased 10m shares from its largest shareholder at a price of 500p per share.At the end of last week Numis Securities reiterated its 'buy' rating following the group's pre-close trading statement issued the previous day. The group has two new hospitals that were expected to be opened in the first half, although it confirmed this would be marginally late with their opening now scheduled for the first week of July. Also on the up was Premier Oil, which has continued its programme of asset disposals by selling off its stakes in the Scott, Telford and Rochelle fields in the North Sea for $130m in cash. UK- and Europe-focused property group Hansteen Holdings made modest gains after revealing it has acquired a portfolio of industrial assets in the Netherlands for €106m. The portfolio comprises 370,000 square feet across 41 estates, mainly in the Randstad area. Merlin Entertainment was also on the up after it announced plans to open a Legoland park in Japan under its operated and leased model. The park will cost around £185m, of which Merlin will invest around £53m over the next three years. The pre-tax cash return on invested capital (ROIC) is expected to be around 20%. Meanwhile, Dunelm was lower after a consensus of analysts gave the stock a 'hold' rating.Online retailer AO World was also hit by broker comment, falling significantly after Shore Capital initiated its coverage with a 'sell' rating, despite describing the company as "fabulous". It issued a note which said: "[...] at a price of 271p per share, a near 61% premium to what we estimate to be fair value, we initiate coverage on AO with a sell recommendation. "The group has a bright future but Shore Capital's message to potential investors is to avoid the stock at current levels. If an eye-watering valuation is not enough to curb enthusiasm for the stock then low returns, margin headwinds and potentially risky earnings certainly should be; no dividend is forecast."FTSE 250 - RisersNMC Health (NMC) 505.00p +5.21%Cable & Wireless Communications (CWC) 50.15p +3.53%Petra Diamonds Ltd.(DI) (PDL) 195.90p +3.43%Hiscox Ltd (CDI) (HSX) 698.00p +3.10%Dairy Crest Group (DCG) 476.40p +2.98%Debenhams (DEB) 69.20p +2.90%Genus (GNS) 1,135.00p +2.81%Senior (SNR) 283.50p +2.64%Man Group (EMG) 104.90p +2.64%Ted Baker (TED) 1,810.00p +2.61%FTSE 250 - FallersRiverstone Energy Limited (RSE) 920.00p -4.22%Dunelm Group (DNLM) 829.00p -3.88%AO World (AO.) 260.80p -3.83%Evraz (EVR) 89.75p -3.29%Soco International (SIA) 406.10p -2.68%Rank Group (RNK) 165.50p -2.65%Crest Nicholson Holdings (CRST) 340.80p -2.60%Redrow (RDW) 275.60p -2.37%Mitchells & Butlers (MAB) 387.30p -2.12%Booker Group (BOK) 130.10p -2.11%NR