Renishaw was rising after it released an unscheduled trading update late on Tuesday. Numis upgraded its profit forecast by 30% and claims that it expects consensus to follow suit. Renishaw also had its "overweight" rating restated by Barclays in a research note issued on Wednesday. The firm announced late yesterday that its first-half sales were 37% higher than the year before at an unaudited £224m and profit before tax of £55m, up 115% year-on-year.Construction stocks were increasing ahead of the Federal Reserve's last policy meeting scheduled for Wednesday evening. Galliford Try and Interserve were both on the rise. Both companies released trading updates today revealing they have continued to perform inline with expectations.Meanwhile, mining stocks were falling again on Wednesday as gold futures continued to drop. This included Vedanta Resources and Petra Diamonds, which was given a "buy" rating by Numis. The broker said: "Petra Diamonds is our favoured diamond play on the UK market. With quality assets and management providing a solid platform, we believe Petra has the best organic growth profile in the diamond sector."FTSE 250 - RisersRenishaw (RSW) 2,215.00p +7.58%Restaurant Group (RTN) 670.00p +4.20%Interserve (IRV) 552.50p +4.05%Northgate (NTG) 610.50p +3.91%Ocado Group (OCDO) 400.40p +3.44%Ladbrokes (LAD) 106.00p +3.41%Galliford Try (GFRD) 1,272.00p +3.00%TalkTalk Telecom Group (TALK) 312.00p +2.97%Hunting (HTG) 502.00p +2.89%Laird (LRD) 322.30p +2.77%FTSE 250 - FallersVedanta Resources (VED) 535.50p -4.29%Debenhams (DEB) 74.50p -3.43%Jimmy Choo (CHOO) 170.10p -3.35%Bwin.party Digital Entertainment (BPTY) 107.40p -2.98%Drax Group (DRX) 410.40p -2.96%Petra Diamonds Ltd.(DI) (PDL) 194.50p -2.70%Cairn Energy (CNE) 169.30p -2.65%Zoopla Property Group (WI) (ZPLA) 191.00p -2.55%Entertainment One Limited (ETO) 303.30p -2.54%Afren (AFR) 40.79p -2.39%