As long as there is yield on BitAssets , a big whale can :
Short to himself with tens of millions of BTS , generate huge amount of BitAssets , hold for 1 month , and cover the short order himself while getting yield (interest ) .
As long as he can cover before margin call price or expire day , it'll be a risk free operation for him , and he has no reason not to do that .
So huge amount of BitAssets was created , but that's not reflecting the actual demand for BitAssets in the real world . Ok , that's not a big deal either .
But with that kind of huge short order , outside speculators who want to buy more BTS , they don't have to buy it at normal price . They can just wait until someone make
the above move , then force the price down in order to margin call the order to pick up the bodies . So as long as some whale is opening new short orders to himself just for collecting the interest(yield) , it not only create false demand for BitAssets , but also increasing the chance of someone trying to push the price down .
If the big whale can watch the price 24/7 and can cover at anytime , he'll be good . But he can't , and the attacker will be betting on that .
Also the big whale maybe too ignorant to realize the attacker can in fact margin call him while he is sleeping , so he'll still dare to do the above operation just for collecting yield and assumes zero risk .