9 Meters Biopharma (NASDAQ: NMTR) stock is down 60%. NMTR stock doesn't seem to have any immediate trigger for this price fall though. All that it's really possible to see at this point is that the selling started pretty much the moment the premarket opened this morning. Not in huge volumes, but 5,000 here and a 1,000 there will move prices in the thin markets of that time of day.
We can see the selling start here and it really is at the very open of the premarket. The closing price last night was 67 cents, the opening trade was at 27 cents. If we look more closely then the fall started after hours last night - it was down 20 cents by 4,30 pm.

9 Meters Biopharma stock price from NASDAQ
As to why the wave of selling no, sorry, we're as much in the dark as anyone else. There's nothing in the usual places. No announcements to Edgar at the SEC. Nothing on the newswires, nothing in the search engines. It just happened.
Normally when this sort of thing happens we can see a couple of trades - usually very early morning - which are so outside regular trading ranges that we know isn't someone attempting to manipulate. And so we recommend going against the price move, as it will revert once the markets and liquidity return. However, that doesn't quite apply here. The fall was immediately after hours so perhaps there was some news release not picked up more generally. But the real point about that is that in the just into after hours period there is still liquidity. So it's much less likely to be a manipulation if it started then.
The one thing we are sure about. As we don't know the reason for the move in the 9 Meter Biopharma stock price we're not going to recommend a trade in it. Trying to trade a moving share price without any idea of why it's moving just isn't sensible to us.