There is ALWAYS just as many shares being bought as sold. You need to define your terms better than they do on TV. BTW - What's a "margin clerk"? Are you taking about someone at a broker that used to actually call people up when they had a margin call? That's all done with computers now.
As boomers get older both their companies and fund managers are holding their shares. More and more they find they(the managers) do not need to take any risk because nobody expects much in the way of returns and doing nothing(SPX ETF or equal returns) beats bank interest even with their FAT management fees taken out by a wide margin. So they apply some static dollar cost averaging and let their bots do the work while they are off playing golf.