how it's done

At last, for technologically-challenged me, this made Alg Trading understandable:

Extract:

the computers are able to do something normal buyers and sellers can't do. They can pick a price they want a security to trade at and then fill in all the necessary trading volume needed to get the price of the security to that point. In other words, you can program computers to rig markets.

In this new rigged market capitalist model, the corrupt bank picks the price it wants a security to trade at and the computers buy and sell with each other until that price is reached; thus providing an audit trail of trades that looks on the surface like actual price discovery."

In other words, we retail mugs don't stand a chance...


http://www.silverbearcafe.com/private/07.10/mask.html