You dont face any regulations. But small retail traders think anything over $1 is too much
. I'll write and sell you the app you describe for $3000 and then you can sell it to others at any price you want :D
I think you're thinking of negative correlation. Uncorrelated is some thing like long eur and then long or ahort cattle
Yes if 2 things are 100% negatively correlated its a double bet in you example
In your ats you keep track of orders and positions. So if you send an order you keep the order on a map or similar. The order gets filled you remove the open order on the map and add a position to another map