MSGI: if someone gained access to your brokerage account they could sell all your holdings, potentially with market orders, which could in turn mean poor 'fills' and bad sales prices on the illiquid issues. Then they could, in their own account, take a position in a relatively illiquid stock before plowing all your money into that single issue and selling their own holdings at much higher prices. It would be the ultimate in 'front running'. Potentially, they could have even accumulated their own position well in advance of the 'sting' at much lower prices. Some of these OTCBB stock don't require a lot of volume to double or triple ! Just look at what CRLI did in the past week. It just takes a few $100k or even less to make some of these stock fly. The crooks could sell into the strength and easily double their money. Of course it would also be 'happy hour' for other holders of the stock if they were quick enough to sell their holdings before the stock crashed back down. But the crooks would have limit orders waiting to get filled. It would leave you with little recourse and huge losses. If they were clever, it would be very difficult to build a criminal case against them.
I've never heard of the above scenario happening, but it probably has, and just hasn't made the news.