US stocks opened sharply lower Friday after China retaliated against the United States for President Donald Trump's tariffs in a tit-for-tat that escalates a global trade war. The Dow fell 1,000 points, or 2.5%, and the broader S&P 500 was 2.6% lower. The tech-heavy Nasdaq was 3% lower and flirting with bear-market territory " a decline of 20% from its peak in December.