The New York Block Exchange got SEC approval to offer the NYBX IOC Order, that allows participants to interact with NYBX and NYSE liquidity on an IOC basis.  The order became available earlier this week - on 4/16.

Immediate-or-Cancel Order. An order from a broker to buy or sell a security or derivative, usually in large quantities, in which investors have a short period of time to partially or completely fulfill the order before it is cancelled.  An IOC may be considered the opposite of a good 'til cancelled (GTC) order;  it differs from a fill-or-kill (FOK) order because an IOC may only be partially filled, while an FOK must be entirely filled or the whole offer is void.  An IOC is considered a type of day order, but has a much shorter time frame.

Execution Rules. As presented on the NYSE Trader page:

• Execute against the liquidity pool of NYBX and NYSE orders within the NBBO
• Accesses Mid-Point liquidity in NYBX
• Accesses un-displayed liquidity on NYSE
• Unexecuted balance cancelled immediately
• NYBX IOC orders are not routed
• Limit order only
• Minimum Triggering Value not available for NYBX IOCNYBX IOC Order

Contact Info. Direct questions to: Bob Hill at (312) 442-7023 (bhill@nyx.com) or Paul Adcock at (312) 442-7046 (padcock@nyx.com) or your Relationship Manager at RelationshipMgt@nyx.com. For further details, go to: [NYSE Trader Update, 1/16/12].