Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Candy Crush got smashed today when its maker, King Digital Entertainment PLC (KING.DL) fell 13% after reporting earnings.

So what: Revenue in the first quarter nearly tripled, to $606.7 million, but was only slightly higher than $602 million last quarter, showing signs that Candy Crush's popularity is fading. Profit was up from $52.7 million a year ago, to $127.2 million, but was down from $159 million a quarter ago. 

Now what: When you come public with a single product that drives your results, the pressure is on to come up with your next product, especially in the fast-moving app business. King Digital and its investors are finding that out quickly, and I still wouldn't be buying the stock today. App and game success is fleeting, and just because you caught lightning in a bottle once doesn't mean you can do it again.