OREANDA-NEWS. October 11, 2016. As announced in Equity Trader Alert #2016 - 224, The Nasdaq Stock Market (“Nasdaq”) will be modifying the functionality of Post Only orders. Pending SEC approval, Nasdaq will implement the changes effective October 31, 2016.

The modified functionality will allow Post Only orders for securities trading at or above one dollar to lock contra-side non-displayed orders resting on the Nasdaq book (“Exchange book”). In addition, Nasdaq and Nasdaq BX (“BX”) will be modifying the functionality of Post Only orders for securities trading under one dollar (note: the functionality of Post Only orders for securities trading at or above one dollar on BX will not change).

Nasdaq and BX will also introduce a new “Reactive Trade-Now” option on FIX and RASHport protocols, providing participants the ability to specify on the original order that once posted on the Exchange book, if the order is locked by a displayed contra-side order, the resting order will attempt to remove liquidity against locking contra-side orders up to its available size; any unexecuted portion of the resting order will remain posted at its price, with no change in order priority.

Please see additional details here.