I'd say the same reason why gold goes up is applying to the markets at this point , that is fear ,fear and hope for some that the market won't sustain it's actual growth and that all stocks could plunge wether or not they're gold stocks even as gold would climb .

It's the market people fear... and gold stocks for most of them have far exceeded broad market growth over the last year so i'd say some think they're more vulnerable to a turnover , many gold stocks have seen their SP grow by hundreds or thousands of percentage point from their lows so some may think they're overbought and could go down as near year end approaches .

But i think some more will jump the bandwagon if gold sustain the kind of increase we're witnessing now especialy in cies. that succeeded in avoiding endebtment or hedging .

Nervousness seems to have got a hold of investors over the last few weeks and profit taking has hit the markets big time so if armageddon does'nt happen in the short term those stocks you figure are 25% undervalued could pick up the lag eventualy .

Just my opinion or theory if u will .