Apple (NASDAQ:AAPL): Piper Jaffray believes that short supply of the iPhone 5S could weigh on opening weekend sales numbers. The firm continues to assert that Apple could sell 5 million or 6 million iPhone 5S/5C units in 11 launch countries during the first weekend, which starts Friday morning. Piper’s work indicates that demand for the phone is healthy, but the firm says some may view a 5 million or 6 million opening weekend number as a disappointment, since Apple will include China as a launch country for the first time. The firm thinks that if Apple doesn’t release a weekend sales press release, it’s likely because sales were less than 5 million units, which is the year-over-year comparison from the iPhone 5 launch. Piper maintains an Overweight rating on Apple shares with a $640 price target.