Probably because it's ADR is listed on the OTC. Also, while NILSY is the world's biggest Pd producer, it is recovered only as a byproduct of copper and nickel mining. It certainly has a much better cost structure than PAL. PAL gives the investor exposure to some Pd and a whole lot of toxic debt.
That makes sense. Too bad they are listed on LSE instead of NYSE.
NILSY is primarily a producer of nickel and copper, but their PGM production generated ~27% of sales revenues in 2012, so they are well-leveraged to palladium and platinum metal prices. They are profitable, pay a decent dividend, and in a recent strategic review, have stated that they will examine options for raising the profile and role of the PGM business.