NEW YORK—U.S. stocks ended sharply lower in a broad sell-off on Friday, ending a week buffeted by strong economic data, corporate tax hike worries, the Delta COVID-19 variant, and possible shifts in the U.S. Federal Reserve’s timeline for tapering asset purchases. All three major U.S. stock indexes lost ground, with the Nasdaq Composite Index’s weighed down as rising U.S. Treasury yields pressured market-leading growth stocks. They also posted weekly losses, with the S&P index suffering its biggest two-week drop since February. “The market is struggling with prospects for tighter fiscal policy due to tax increases, and tighter monetary policy due to Fed tapering,” said David Carter, chief investment officer at Lenox Wealth Advisors in New York. “Equity markets are also a little softer due to today’s weak Consumer Sentiment data,” Carter added. “It’s triggering concerns that the Delta variant could slow economic growth.” A potential hike in corporate taxes could …