I am not into IB but I do maintain my portfolio. I did not sell my stocks even during the turmoil because most of them were growth stocks and I believed on the companies' abilities to deal with the situation. It seems, the strategy is finally paying off...
My main principle is to focus on the growth stocks and buy stocks when they go down due to some outside elements while they retain their growth potential. In fact, I bought quite a few stocks during the fall-down while others were selling. It was a risk but if you look at the companies' performances, it was not such a big risk as it was perceived in the outside world.