Facebook is down almost 9% since the news broke that Cambridge Analytica misused data on up to 50 million users. What we are seeing in Facebook's stock is the opposite of irrational exuberance. For rational investors with a reasonable investment horizon, this is a good time to buy Facebook. The use, and misuse, of Facebook data is now in the forefront of the public's attention. Therefore, the probability that significant new laws will be enacted that justify a 9% loss of value for Facebook is virtually zero.

Source: Forbes March 20, 2018 16:41 UTC