Amazon stock plunged 8% in premarket trades Friday. The e-commerce giant reported second-quarter results that topped Wall Street's expectations, but gave a mixed outlook. For the current quarter, Amazon predicted sales of $176.75 billion at the midpoint of its range, compared with analyst expectations for $173.27 billion.

Stocks slumped and Treasury yields fell sharply Friday (August 1) after a weak report on hiring and the latest gyrations in US trade policy shook Wall Street. The S&P 500 fell 1.8% and is on track for its biggest decline since late April.

The last day of a busy week ends with the first greater-than-1% move in either direction in more than a month.