U.S. markets opened lower on Friday following a disappointing August jobs report which showed that employers added just 173,000 new jobs in the month. Economist forecasts had been for 220,000 jobs added. The unemployment rate ticked down to 5.1 percent, better than the 5.2 percent which had been expected. In corporate news, Facebook (FB) said WhatsApp now has more than 900 million monthly active users, that's up 100 million since April. Gap (GPS) said sales at its Old Navy stores rose 6 percent in August, but Banana Republic saw sales slump 11 percent. Amazon's web services unit is buying Elemental Technologies, a backend mobile video service, for $500 million. Walt Disney unleashed a massive toy and marketing blitz for Star Wars: Episode VII - The Force Awakens. The film is still a few months from being released. but Toys R Us and Uber are two of the companies participating in what's being called 'Force Friday.' Apple Music (AAPL) was listened to by 44 million U.S. users during July, its first month, according to ComScore. The monthly performance put Apple's new music service in the top 15 for U.S. smartphone apps. And, good news for those hitting the road over Labor Day weekend: The national average price of gasoline this weekend will be its lowest at this time of year since 2004. That's a result of low oil prices and a quiet hurricane season that has allowed refineries to churn out gasoline and diesel. TheStreet's Ruben Ramirez reports from the Nasdaq Marketsite in New York.