After a positive start, UK stocks had dropped into the red by Wednesday lunchtime with nerves surrounding Greek politics dampening sentiment, as investors awaited a policy decision later on by the US central bank.London's FTSE 100 was down 0.2% at 6,797 by midday, pulling back after reaching an intraday high of 6,863 early on.Greek stocks were down nearly 7% in the aftermath of the general election on Sunday, where anti-austerity party Syriza won the vote and announced it would form a coalition.New prime minister Alexis Tsipras told his cabinet on Wednesday that he would move quickly to renegotiate terms of the bailout with Greece's creditors. He said he wanted to "radically change the way that policies and administration are conducted in this country"."The first meeting of the new Greek government today has triggered a sell-off in Athens and increased nerves around Europe. The FTSE has not been immune from this," said analyst Alastair McCaig from IG. "Nerves continue to get the better of traders as the wait for meaningful government policies from Athens continues to preoccupy investor thinking," he said.US stock futures were mixed ahead of the opening bell, though the Nasdaq jumped strongly after positive reactions to results from tech heavyweights Apple and Yahoo on Tuesday evening.Apple's shares jumped after the close after the smartphone and tablet group reported a massive 30% year-on-year increase in quarterly sales to $74.6bn and a record quarterly net profit of $18bn. Meanwhile, results from Yahoo were also welcomed, along with the announcement that it will spin-off its $40bn stake in Chinese ecommerce firm Alibaba.With little economic data on tap on Wednesday the focus will be on the outcome of the Federal Open Market Committee (FOMC) meeting at 19:00 with investors waiting for hints about when the US central bank will begin to hike interest rates.With no press conference scheduled and no new projections expected, analysts at Danske Bank said the "focus will be on the tone of the statement". They said: "We expect only small changes to the statement and most importantly we expect it to repeat that the FOMC can 'be patient in beginning to normalise the stance of monetary policy'."Experian, Anglo and ARM riseCredit-checking firm Experian was a high riser after the company outlined strategic and capital framework plans to "deliver annual average growth in organic revenue in the mid-single digit range". The company also said it has the potential for "strong growth" in earnings per share.Mining giant Anglo American impressed by meeting forecasts with its fourth-quarter output results with improvements in iron ore, coal and platinum and declines in copper, nickel and diamonds. However, sectors peer Antofagasta was lower after a production update disappointed.Chip designer ARM Holdings was in positive territory after better-than-expected results from customer Apple showed strong demand for smartphones.Third-quarter sales rose at Johnson Matthey but shares slumped after the chemicals group's underlying profits growth slowed due to continuing issues with Anglo American Platinum.Business management software group Sage underwhelmed after saying it made a "solid start" to the new financial year and remains on track to hit its growth targets.On the FTSE 250, oil producer Afren rebounded after a sharp plunge in its share price the previous session on the back of funding concerns. Market MoverstechMARK 3,070.29 +0.23%FTSE 100 6,796.75 -0.22%FTSE 250 16,372.62 +0.11%FTSE 100 - RisersExperian (EXPN) 1,200.00p +3.00%Anglo American (AAL) 1,109.50p +1.79%SABMiller (SAB) 3,494.00p +1.69%Weir Group (WEIR) 1,667.00p +1.65%Dixons Carphone (DC.) 426.00p +1.57%ARM Holdings (ARM) 1,047.00p +1.55%Severn Trent (SVT) 2,180.00p +1.35%Capita (CPI) 1,106.00p +1.19%Pearson (PSON) 1,333.00p +0.91%Persimmon (PSN) 1,568.00p +0.84%FTSE 100 - FallersMorrison (Wm) Supermarkets (MRW) 187.80p -5.39%Johnson Matthey (JMAT) 3,322.00p -5.00%Standard Chartered (STAN) 907.70p -3.61%Babcock International Group (BAB) 981.50p -3.01%Sage Group (SGE) 473.10p -2.25%easyJet (EZJ) 1,750.00p -2.18%Tullow Oil (TLW) 362.10p -2.16%Antofagasta (ANTO) 679.00p -2.09%ITV (ITV) 221.50p -1.95%InterContinental Hotels Group (IHG) 2,673.00p -1.87%FTSE 250 - RisersAfren (AFR) 5.90p +18.00%Crest Nicholson Holdings (CRST) 398.00p +4.82%Intermediate Capital Group (ICP) 502.00p +4.37%Game Digital (GMD) 275.50p +4.28%Enterprise Inns (ETI) 110.10p +4.06%Serco Group (SRP) 162.00p +3.65%Saga (SAGA) 172.50p +3.29%Nostrum Oil & Gas (NOG) 553.00p +2.98%Greencore Group (GNC) 300.10p +2.77%Redefine International (RDI) 54.55p +2.63%FTSE 250 - FallersVedanta Resources (VED) 393.30p -4.26%Supergroup (SGP) 937.00p -3.85%Jimmy Choo (CHOO) 173.00p -3.35%Zoopla Property Group (WI) (ZPLA) 184.00p -3.16%Rightmove (RMV) 2,370.00p -2.99%Kaz Minerals (KAZ) 186.70p -2.76%Booker Group (BOK) 155.00p -2.58%Mitchells & Butlers (MAB) 420.70p -2.41%Petra Diamonds Ltd.(DI) (PDL) 165.00p -2.37%Infinis Energy (INFI) 185.00p -1.91%