Pfizer's PFE.N vaccine partner BioNTech BNTX.Oalso fell 6.2%. By Sinéad Carew Jan 11 (Reuters) - U.S. stock indexes gained ground on Tuesday with Nasdaq leading the advance as investors were relieved that Federal Reserve Chair Jerome Powell's testimony to Congress did not include any major surprises. While investors will anxiously watch inflation data due out on Wednesday, Cruz notes that they are already prepared for an elevated number with consensus forecasts for a 7% increase on a year-on-year basis for the headline Consumer Price Index (CPI).