Markets start the month of September on a down note.

The markets started the new month a little lower as September typically sees an uptick in volatility. The Dow 30 lost 12, the S&P 500 lost 4, and the Nasdaq 100 closed down 18. Traders expect that the Canada discussions will be a focus during the week until Friday when all eyes will be on the jobs numbers.

Nike (NYSE: NKE) shares sold off 3% today as the company released an ad campaign for their 30th anniversary called "Just Do It" in which one of the ads features former NFL player Colin Kaepernick. He was the first NFL player to kneel during the national anthem.

Amazon (NASDAQ: AMZN) shares officially hit the magic number to make them just the second company to have a market cap of $1 trillion. The company also announced they would be challenging Facebook and Google's advertising businesses. Amazon says that they can be more effective as they have the data on people's shopping habits.

Goldman Sachs (NYSE: GS) which previous removed their coverage of Tesla (NASDAQ: TSLA) for conflict of interest reasons reinstated their coverage today with a sell rating. The company had suspended their coverage when they were tapped to advise on the possibility of going private. Now that those plans have been scrapped Goldman says Tesla is a sell with a price target of $210, slightly better than their previous target of $195.

Seagate Technology (NYSE: STX) and Western Digital (NYSE: WDC) were the big losers in the S&P 500 today as Evercore downgraded both companies. Seagate was downgraded to underperform and WDC was downgraded to inline citing pricing pressures on memory as the driving factor.