Actually it is worse than that Danvestor. When a stop loss is...

Actually it is worse than that Danvestor. When a stop loss is triggered the order becomes a market order, so there is no guarantee that Joe Bloggs will get $9.40 or anything close. The investment bank can use 1 share bot orders to drive the price down to the stop price and then scoop up the whole of Joe Bloggs holding way below the trigger of $9.40. Setting a stop loss doesn't mean you will get that price. It just means you have sold maybe one share at that price and the rest at the lowest price possible. Because the small retail buyer can't buy small parcels to match the bots (commissions would bankrupt you) these small orders can walk the price down at no cost to the bot owner who isn't paying any commission.