It's common for many if not most companies. The guiding principle of buy on the rumor, sell on the news often means that a lot of investors realize gains after

It's common for many if not most companies. The guiding principle of buy on the rumor, sell on the news often means that a lot of investors realize gains after a big positive news event driving the price down. There were drops like that, iirc, when Apple announced the change to Intel and I think also the iPhone announcement. The drop is generally short-lived as the long-term investors buy in.