U.S. stock indexes firmed on Friday after a three-day pullback for the S&P 500 and the Nasdaq, as investors looked to data that is likely to show accelerated jobs growth in February. Federal Reserve Chair Jerome Powell on Thursday maintained the central bank's dovish stance to support maximum employment and said inflation was not a worry at the moment. His comments disappointed investors who expected him to act on the recent spike in the U.S. 10-year Treasury yield that has set the S&P 500 and the Nasdaq on course for their third straight weekly decline.