Abstract: Methods and systems for facilitating trading of securities, preferred methods comprising receiving a first buy or sell order from a first user; calculating a block price range; determining that said first order is reasonably priced; transmitting to a second user a notification that a reasonably priced order is present, but without notifying said second user of the side; receiving a second order from said second user, wherein said second order is a contra to said first order and nearly matches but does not cross said first order; transmitting a contra order notification to said second user after said second order is received, said contra order notification indicating that a nearly matching contra order is active; receiving a third order from said second user, said third order being a contra to said first order and crossing said first order, and executing a trade comprising said first order and said third order.

Abstract: One exemplary aspect comprises a method comprising: (a) receiving data indicating that one or more orders for a specific security in one or more trading systems are available for aggregation into a potential block of at least a specific size; (b) transmitting data sufficient to enable a trading interface in communication with a first trading system to display an indication of the existence of the potential block and that at least some orders in the block originated from a second trading system in the one or more trading systems, the second trading system being separate from the first trading system; and (c) receiving from the trading interface a contra order in the first trading system that crosses the potential block. Other aspects comprise related computer system, components, and software.