Heavy volume. Even with electronic trading it takes a while to get everything computed.
It would be very, very unwise to pick a bottom now but often heavy volume on the downside indicates capitulation.
But I don't know what else to do but ride it out. I really loathe the thought of selling out and losing half my assets. Just keep going in to work every day, paying the bills, taking care of the folks, and putting off retirement a few more years...:-(