Ok mate but as long term investor how can I protect myself...

Ok mate but as long term investor how can I protect myself hen....Imagine I have a large position and one company and I go on a 1 month holidays disconected from news or my life is so busy that I am also disconected from the new and the the company release some of those horrible market anouncements and market opens already 8% down and in the folowwing fortnighnt ends up 40% down just like we saw with A2m. My point is that even in long term investments I personally feel like I need to define the amount of risk I want to have and stick to it. In the scenarion above a stop loss would have saved me. Would you have any other sugestion to help long term investors that do no want to keep an eye all the time...cheers