美联储维持利率不变，对通胀前景信心减弱

盘前异动股：联合包裹、微软、卡特彼勒等公司股票表现活跃

GDP grew at a 2.3% pace in the fourth quarter, less than expected

微软因发布疲软业绩展望而股价下跌，但分析师仍持乐观态度。