African Barrick Gold rallied after Nomura reiterated a 'buy' rating for the stocks and raised its target price from 155p to 250p, saying the miner's move to cut costs was ahead of the industry.Alent, supplier of advanced surface treatment plating chemicals and electronics assembly materials, rebounded following a slump earlier in the week and a sharp fall in early August when it reported a drop in half-year profits. Kenmare Resources declined after the miner posted a loss before tax of $9.2m for the first half, compared to a profit before tax of $38.8m last year.Polymetal International tumbled as the gold and silver miner posted a first-half net loss of $255m, compared with a $157m profit a year earlier.FTSE 250 - RisersAfrican Barrick Gold (ABG) 177.70p +4.35%Alent (ALNT) 358.20p +3.56%EnQuest (ENQ) 126.20p +3.44%Enterprise Inns (ETI) 144.00p +3.00%Soco International (SIA) 386.80p +2.74%Premier Oil (PMO) 364.10p +2.48%Hochschild Mining (HOC) 227.80p +2.11%Pennon Group (PNN) 693.50p +1.84%IG Group Holdings (IGG) 563.50p +1.53%Kazakhmys (KAZ) 307.20p +1.45%FTSE 250 - FallersKenmare Resources (KMR) 26.72p -9.58%Polymetal International (POLY) 680.00p -8.23%Berkeley Group Holdings (The) (BKG) 2,091.00p -5.98%Regus (RGU) 174.80p -5.51%Countrywide (CWD) 560.00p -5.08%Halfords Group (HFD) 369.80p -4.15%Henderson Group (HGG) 167.10p -4.08%NMC Health (NMC) 321.90p -3.97%Imagination Technologies Group (IMG) 252.60p -3.88%Morgan Advance Materials (MGAM) 294.60p -3.54%RD