Stock futures slid ahead of the start of trading in U.S. financial markets on Friday as investors fret about the health of technology companies and the path of interest rates. S&P 500 futures were down 1.1%, or 71 points, as of 8:30 a.m. EDT, and Dow Jones Industrial Average futures dropped 0.7%, or 316 points. Nasdaq Composite futures declined 1.5%, or 373 points. On Thursday, the stock market had one of its worst days since a springtime sell-off. The S&P 500 sank 1.7% on the day, falling