That's difficult to predict since the largest part of the selling (that drove AGNC's price down sharply on high volume) came from institutions who owned more than 1M shares of AGNC and dropped it on the market. Such trading (which we have called "flash crashes") is done by computers that are programmed to sell at certain points (i.e., prices). What those decision points are, we have no idea and are closely guarded secrets of those instituions.
We've seen at least two such "flash crashes" in the past few weeks; more could happen in the next two weeks. The disciplined investors will sit back in cash and wait to see what earnings (and forecasts) come from AGNC's management on 10/29. The more venturous investors (speculators really) may buy some shares after each "flash crash" in the hopes that this one is the last, with prices recovering in the days ahead. Good luck to all.