First I'd like to say thanks for Don Bright for posting a link describing this, however as I started reading it I realized that it was just over my head. Some general questions: 1)In another thread someone talked about how IBs SMART router does not search for hidden liquity pools, but only searches for the best "displayed" price... Okay well why on earth would you want your order to be hidden. That's like sending a buy limit order @ 50.50 and having 50.49 being filled before you? 2) They say that hidden liquity pools are for algo trading... not sure I understand why. 3) An estimate on % of orders hidden vs displayed 4) This article says something like yada yada yada, and then once the hidden order becomes displayed... do these orders have a parameter setting where is becomes displayed after x seconds or after a certain condition?