http://www.theverge.com/2016/7/25/12269466/nintendo-stock-plunge-pokemon-go
quote:
Pokmon Go is a collaboration between The Pokmon Company and Niantic Labs, the developer who previously created the similar AR game Ingress as part of Google. This apparent revelation caused shares to plummet in Monday trading, with the stock dropping 17 percent at one point, representing about $6.4 billion in value; as Bloomberg notes, Tokyo stock exchange rules prevent share prices from moving more than 18 percent in a single day.