Daal,
I checked, even as a BVI (or any other foreign company for that matter), you will have to pay HK profit tax if your operation is conducted in Hong Kong, regardless of where your company is domiciled.
That's definetely not my understanding.
If not trading HK stocks, it seems you could either trade under ur personal name, a bvi company or a HK company tax free. I'm surprised profits from trading foreign stocks would qualify as taxable profits in HK, although things are not moving for the better there.
Besides if you are the director of the HK Ltd you trade through, you can pay yourself up to 120k HKD per year allowance/salary tax free. Not much but still the beginning of an income you can show. Dividends are tax free in HK if you need to distribute larger amounts.
You definetely should check with a CPA, and possibly a couple of them, it's possible they don't all have the same interpretation of the law. The Cpa should also be willing to defend its positions towards the ird, HK companies claiming tax free profits do get audited - which doesn't mean the ird finally doesn't accept their claims