Do you guys margin trade on polo? You can close your entire position via a market order, these flash dumps are likely a margin long closing out via market and is taking out stops along with it. FCT float is small and orderbook at times can thin out, anyone with 20k+ long closing out on margin will cause that type of move.
Seems like a silly thing to do vs selling a bit at a time so as not to affect the price you are getting as much.
I think that's what CocoLibre is getting at. People unaware it's possible to sell a little at a time. You're given the option of 'close' which closes the entire position, but it's not clear that making a new short sell order achieves the same thing in custom amounts. I was unaware of this until a few weeks ago.