iPHONE 7: This is what happens to Apple stock before and after an iPhone release

In a few weeks Apple will unveil iPhone 7. The launch is crucial for the company because its sales are in decline and it is not clear how Apple will get out of this rut until 2017, when a much more dramatic update to the iPhone is expected.

So, should you buy AAPL stock now, and hope for gains as sales of iPhone 7 and next year's model kick in? Or has the stock reached a peak, meaning you should cash out now while the going is good. AAPL closed at $108.18 last week. It started the year at about $105, so its performance year-to-date has basically been flat.

We looked at the price of Apple stock for all iPhone releases from iPhone 4s onwards, and calculated whether the launch of an iPhone is good or bad for the stock if you bought it on the day the new phone was released and held it until the day of the release of the next device, roughly a year later.

Here's a chart of AAPL's progress (click to enlarge):

The numbers show that the launch of a new iPhone is not a solid guide to the direction of AAPL afterward. Although the stock generally rises, it lost 32% of its value in the year after iPhone 5 and gained only 16% after iPhone 6s. From that launch until today AAPL has given up another 4%:

• iPhone 4s Oct 14 2011 - $55.19
• iPhone 5 Sept 21, 2012 - $91.96, up 67%
• iPhone 5s Sept 20, 2013 - $62.86, down 32%
• iPhone 6 Sept 19, 2014 - $97.19, up 55%
• iPhone 6s Sept 25, 2015 - $112.31, up 16%
• Today: $108.18, down 4%

Generally, Apple's stock rises nicely. It has gained roughly double its value since iPhone 4s through to today.

So the bottom line is that, historically, trying to time Apple stock is a risky bet - holding it for the long term is where the real gains are.