September's Rally Rolls On

September has been a good month -- a very good month -- for stocks.

The Dow Industrials have closed lower just three times so far in September; and with one week to go, all three major averages here in the U.S. are up at least 3%.

It was a long haul yesterday, but the blue chip average eked out a 19-point gain. The Nasdaq and S&P 500 fell modestly. This morning, U.S. stocks are signaling a higher open, with Dow futures gaining 55 points.

Today is a day to watch volume and volatility. It's a quadruple witching session, which means contracts for stock index futures, stock index options, stock options, and single stock futures all expire. The event happens four times a year and has been historically positive for the market.

In corporate news, Wal-Mart (NYSE:WMT) and Amazon (NASDAQ:AMZN) are breaking up. The world's largest retailer is pulling Amazon's Kindle tablets and e-readers from its stores, website, and Sam's Club division. The Kindle line doesn't turn a big profit for retailers, and some of them, including Target (NYSE:TGT), are tired of being used as a physical showroom for's devices. Best Buy (NYSE:BBY), Office Depot (NYSE:ODP) and Staples (NASDAQ:SPLS) will continue to sell the Kindle.

Apple's (NASDAQ:AAPL) newest iPhone lands on store shelves today and industry analysts expect the iPhone 5 to be the bestselling mobile device of all time.

But it's not all warm and fuzzy feelings for Apple. The tech giant is facing a heap of criticism for its new Maps app that replaced the popular Google Maps in iOS 6. Some say Apple's Maps app is the biggest drawback of  the iPhone 5, and Google Maps was much better. Critics say there is too much mislabeling -- or even missing -- landmarks and cities in the new app, and it lacks the popular "Street Views" that Google had featured. Apple says it's working on improving the service, and it will get better as more customers use it.