mfs preopen, page-27

Thanks....
Forget the bid then, why does a stock that announces that its Stella business is outperforming previous guidance and has more than manageable debt this year, fall by nearly 30% in a week. Which is over 20% more than the broader market and more than the sector it is in?

Does anyone have any theories on this other than what can be found by reading the paper, reading announcements or talking to the company, ie. has anyone heard any rumours etc as to what could cause such price action?