Not all the time but most likely this is really the case been happening where market is highly reactive to news this is why people are really very keen on looking for these kind of information
specially on upcoming events but most of the time where news pops out from nowhere leaving lots of questions in mind on what the heck happened?..
This is the most common situation, when we see a dump or a pump, we start looking for information to find out what it is related to. But we get such information after the market has reacted to the event, and we would like to know in advance about the upcoming pumping/dump in order to make the right decision when opening an order.