Previously they had their huge copper by-products realizing and/or hedged at $3.00+ copper leading to the sub $650 AISC. With hedges coming off and realizing spot pricing they are now guiding for $1000 AISC-ish in 2016.
Think this was probably priced in and has lead to DPM's big decline but the worst news may be priced in.
I wasn't all that impressed when they announced the $1000 AISC and sold most but now that may be looking like a mistake. Also looked at Bulgaria during a project for work and the country is a basketcase so not impressed they will be opening second mine there so I decided to sell.
that being said, I bet DPM has bottomed here so I should probably hold a few as it is a laggard.