Nasdaq PSX TotalView-ITCH

Dataset ID: XPSX.ITCH

Nasdaq PSX disseminates full depth-of-book data for their exchange through their TotalView-ITCH feed over the MoldUDP64 protocol, which Databento receives over UDP multicast in our NY4 data center.

PDF specifications are available on Nasdaq's website for Nasdaq TotalView-ITCH and MoldUDP64.

Timestamps

Nasdaq PSX TotalView-ITCH messages received by Databento have at most one timestamp, which has nanosecond precision. As with all of our datasets, we also collect a ts_recv timestamp when the packet was received by our capture server.

The extra field ts_in_delta does not convey any additional information for this dataset, and is equivalent to ts_recv - ts_event.

Databento Field	TotalView Field	Description
`ts_recv`	N/A	The capture-server-received timestamp.
`ts_event`	Timestamp	The matching-engine-received timestamp.

More details about our timestamps are available in our timestamping guide.

MBO normalization

Order lifecycle messages

There are seven message types in TotalView that change the state of the order book. Databento normalizes these messages to MBO records as follows:

Add Order - No MPID Attribution: Add
Add Order with MPID Attribution: Add, but the attribution field is not included
Order Executed: Trade, Fill, then Cancel
Order Executed with Price: Trade, Fill, then Cancel, but the initial Trade is omitted if the message is marked as non-printable
Order Cancel: Cancel, with the quantity indicating the number of shares to remove from the display size
Order Delete: Cancel, with the quantity indicating the current display size of the order
Order Replace: Cancel with the previous order_id, followed by Add with the new order_id

All Trade records will have order_id set to 0, because Nasdaq does not provide information about the aggressor's order. Normalized records from the same TotalView message will have the same sequence.

Trade messages

TotalView also has two messages for providing execution details for match events against non-displayed orders or cross events.

Databento normalizes both Trade (Non-Cross) and Cross Trade messages is into a single MBO Trade record with side None.

Definition normalization

Definition records are sourced from Stock Directory messages.

Databento Field	TotalView Field	Description
`exchange`	Market Category	Normalized to the MIC code of the listing venue. All Nasdaq-listed instruments will normalize to `XNAS`.
`security_type`	Issue Classification	Identifies the security class for the issue as assigned by Nasdaq. A list of the different values and their meanings can be found in Appendix D here.
`secsubtype`	Issue Sub-Type	Identifies the security sub-type for the issue as assigned by Nasdaq. A list of the different values and their meanings can be found in Appendix E here.