A priori, sure. After the fact, if you have detailed enough data it can be pretty easy to identify the timing of certain events.
It doesn't mean that the reaction is correct or that it won't be undone in the future. But there's a huge difference between "day to day fluctuations are unpredictable" and "day to day fluctuations are inexplicable."
Twitter was also down 7% today do you think that's explained by the Occulus deal?
The reality is the markets react to thousands of individual factors and often small changes lead into positive feedback loops. So, while the timing may be explained by some news breaking the magnitude of change is generally influenced by all those other factors.
Well, we had a couple of strong down days in the stock market over the last couple of days. Lots of momentum darlings like Netflix, Tesla, SolarCity, Pandora, Google, Twitter and Amazon took heavy hits. FB was already down 10% from its top in early March before today, so this was basically coincidence.
