Miners were among the best performers of the day again on Wednesday as risk appetite increased ahead of a policy announcement by the Federal Reserve.The dollar was falling for a third day in a row today before the conclusion of the Federal Open Market Committee (FOMC) meeting, with the central bank widely expected to announce more stimulus as 'Operation Twist' comes to an end.A weaker greenback tends to boost dollar-denominated metals prices as those commodities become more attractive to holders of other currencies. As such, gold futures were at a one-week high today. In London, shares in EVRAZ, Anglo American and Polymetal were among the best performers.Sector peers BHP Billiton was also in demand after selling its "non-strategic" interests in the East and West Browse Joint Ventures (JV), offshore Western Australia, for $1.63bn."Risky assets performing reasonably well today, thanks to greater optimism over the US economy following yesterday's strong wholesale inventories data and warm words from the ISM about the US economic outlook," said market strategist Ishaq Siddiqi from ETX Capital.The Institute for Supply Management (ISM) said yesterday that the US manufacturing sector is "optimistic about growth" in 2013 with 62% of manufacturing purchasing managers it surveyed expecting revenues to be greater year-on-year."The panel of purchasing and supply executives expects a 4.6% net increase in overall revenues for 2013, compared to a 4% increase reported for 2012 over 2011 revenues," the ISM said.Meanwhile, optimism over the 'fiscal cliff' has increased slightly over the last few days following meetings between President Barack Obama and House Speaker John Boehner. ETX's Siddiqi said: "Though talks have so far had little meaningful progress, traders are comforted by the fact that it is at the top of the agenda in Washington. Yesterday, both Republicans and Democrats traded proposals aimed at reaching a budget deal - there is enough cautious optimism out there in the market that a deal can be reached before Christmas."Top performing sectors so far todayIndustrial Metals & Mining 2,688.62 +2.87%Industrial Transportation 2,428.28 +1.22%Insurance (non-life) 1,625.43 +1.07%Mining 19,190.58 +0.93%Industrial Engineering 8,094.36 +0.85%Bottom performing sectors so far todayFixed Line Telecommunications 2,754.53 -0.75%Personal Goods 20,322.81 -0.52%Health Care Equipment & Services 3,831.48 -0.40%Household Goods & Home Construction 8,251.73 -0.38%Real Estate Investment Trusts 2,187.66 -0.36%BC