Mid-caps remained shaky on Wednesday, as investors looked to the Federal Reserve's upcoming policy decision and negative news from Greece continued to weigh on sentiment.As of 14:30 BST, the FTSE 250 was trading 0.23% lower at 17,696.Property developer Berkeley Group topped the risers after posting a 42% jump in full-year pre-tax profit to £539.7m. The company said domestic demand was strong in its core markets of London and the south of England, and the developer has experienced sales price increases in line with those reported in the wider market.Ocado gained after Credit Suisse initiated coverage at 'outperform' with a 466p price target and said Ocado is a market leader in the only part of mainstream grocery that is growing strongly. "We expect advancements in many areas of its business to improve gross margins, as well as additional third-party sales of its fulfillment technology," the bank said.Just Eat plunged as Morgan Stanley initiated coverage at 'equalweight' with a 450p price target, warning "any perceived weakness could now lead to a de-rating and a better entry point."Betfair declined despite meeting analysts' forecasts with a 53% rise in full-year operating profit as product and marketing investment drove record customer activity. Broker Numis Securities raised its rating on the stock from 'sell' to 'reduce', but said its valuation was still "too high".Amlin dipped as analysts at UBS downgraded the stock to 'sell' from 'neutral' and cut its price target to 440p from 460p. UBS said the company has struggled to improve the profit contribution from hubs outside of London and Bermuda, and there are still question marks around some divisions. RisersBerkeley Group Holdings (The) (BKG) 3,429.00p +8.58%Tullow Oil (TLW) 376.80p +4.09%Infinis Energy (INFI) 195.30p +2.79%Soco International (SIA) 191.10p +2.47%Imagination Technologies Group (IMG) 226.80p +2.39%Daejan Holdings (DJAN) 5,725.00p +1.96%Vedanta Resources (VED) 593.00p +1.89%Fisher (James) & Sons (FSJ) 1,351.00p +1.89%Ocado Group (OCDO) 382.70p +1.78%Carillion (CLLN) 334.00p +1.71%FallersJust Eat (JE.) 402.10p -4.76%Betfair Group (BET) 2,426.00p -3.50%Kaz Minerals (KAZ) 225.60p -2.76%Nostrum Oil & Gas (NOG) 540.50p -2.26%Fidessa Group (FDSA) 2,206.00p -2.17%Greggs (GRG) 1,158.00p -2.03%St. Modwen Properties (SMP) 449.00p -1.99%Spire Healthcare Group (SPI) 323.50p -1.97%Paragon Group Of Companies (PAG) 429.40p -1.90%Great Portland Estates (GPOR) 793.00p -1.86%