NBBO execution at public exchange

External question — Personal Finance Stack Exchange Author: Zheng Original post: https://money.stackexchange.com/questions/156212 License: CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ Adaptation: HTML converted to plain text; contact email addresses removed. There are about 16 stock exchanges in the U.S market. According to Reg NMS, broker-dealers have to guarantee at least NBBO price to its customer. My question is if the best ask is coming from say IEX and the broker I am using is not a member to IEX, can my broker still route my order to IEX assuming that my broker is not routing my order to market maker and other brokers and only executing my order at public exchanges.

External answer — Personal Finance Stack Exchange Author: xirt Original post: https://money.stackexchange.com/a/164262 License: CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ Adaptation: HTML converted to plain text; contact email addresses removed. Yes. Most exchanges offer routing capabilities to route orders to other exchanges for this reason. Sometimes this is handled transparently by the exchange. Alternatively, many brokers may use another broker to route orders to other venues where they are not members for this or similar situations.