IB advertises that you can buy and sell across several accounts in a proportional manner. However, that only works if you buy and sell 100% of the shares all at once. So, if you accumulate $50k of AAPL and then you want to sell it in chunks, across the accounts, you end up with leftovers or sometimes even short a few shares. If you enter trailing stop for 50% of the shares and another trailing stop 50% of the shares, it doesn't pull and sell 100% of the shares that you bought, it leaves some leftover if you have an uneven amount. I have been round and round with them and they insist that it is not a problem but I don't want to have a bunch of random shares leftover, or worse, short shares. And I don't want to sell all the shares at once just because their system doesn't work properly if I don't. Makes me crazy!!!! And then they want to me to fill out some form to explain the problem to them after I have explained it several times on the phone. They previously claimed it was because my software wasn't updated but then I updated the software and it still did it. Their solution is to tell me to sell all the shares at once! GRRRR!!!!