ladies and gentlemen start your engines, page-8

That's one possibility.

Another is that other people are day trading the stock on good news and since it isn't moving in the "wanted" direction (probably in this case; the right direction), they cut their losses so they don't need to settle their trade.

If you have spare money and don't need it (like the rest of most buy-and-hold stockholders), just keep to your trades and don't sell at poor prices.

I hold CNX