how they do it:suppose they sell 10 shares at an average price...

how they do it:

suppose they sell 10 shares at an average price of 2$
total they are getting = $20

this triggers margin call etc and pushes the price down to, say, sub $1.60 levels

they buy the 10 shares at $1.70 average
cost is $17

so, they make a net profit of $3 minus the borrowing charges.

if there is trading halt before they can buy back, i think their happiness is pretty much screwed. usually, one bot is programmed to sell, another bot is programmed to buy back. buying back can happen on the same day or across several days. the borrowing part probably contains a condition whereby the hedge funds do not need to 'return the shares back the owner' if there is a trading halt / suspension .. it is possible, i am not sure.