A normal affect of stock price during a major announcement.

It even has a name '"buy the rumor, sell the news"

http://www.investopedia.com/terms/n/news-trader.asp

The idea behind this, simply put, is that if you are in a trade for whatever reason with a stock that has a major announcement coming; you are pretty much at the potential peak at announcement time so it is a good time to get out.

"buy on rumours, sell on news".

There were rumors of slightly better single threaded performance. Stock movements are always relative to expectations, investors knew roughly what was coming but not the exact details.

The stock is down 7% compared to yesterday, but up 500% compared to one year ago.