Today's action was because of one or a few of following
1- Knowing ACTU will go to Russell 2000 small cap from micro cap, one or more funds in macro cap were selling ACTU and other stocks that may leave micro cap. Any Fund holding ACTU since last year probably gained more than 100% in its investment. Similarly, a fund stepped in and got most of ACTU shares.
2- The selling and buying pattern reminded me of RNDC which was acquired a few months ago. Yesterday, a buyer made a 30K purchase just a few seconds before the close. Today, after selling 40k at open to push the price down in the red market, most shares were accumulated at lower price and cost in the last hour.
3- Someone just read 8-k from last Friday and sold on uncertainty. ACTU has cleared that uncertainty this afternoon by releasing a 10-Q commenting on performancesoft questions.
4- Interest rate hike caused some investors to sell so they can reduce their debt.