Ann: Production Update Q4 June 2018, page-23

The market always prices stocks on future earnings.
Next year will have lower production at higher costs with Simberi only having a couple of years left (mainly using low grade stock piles).
This will leave only one mine which adds to risk.

The market is clearly pricing in the lower production, higher costs and higher risk of only having one mine producing in the future.
Clearly they need to buy another mine somewhere, they have some cash available but the problem is all the good stuff has been snapped up several years ago and whats left for sale is mainly over priced or low quality.

Its hard to see how they can grow future production and keep AISC at a reasonable low level to generate sufficient sustainable surplus cash which justifies the current Market Cap of the company.