As for the tape:
- Algorithmic orders are implicitly hidden, because usually only a small portion of the order is released for trading (slice, random slice)
- Routing an order to a less obvious venue
- Discretionary orders. Submit orders deeper into the book than our best bid/offer. This is done to establish execution priority.
- Iceberg Orders. Only display a portion of the order
- Fully Hidden Order. Entire order is hidden.
See attached screenshots.
Ref: Johnson, Barry. (2010) “Algorithmic Trading and DMA.” Pg 261-2.