Also known as the OTC Bulletin Board (OTCBB). An electronic interdealer quotation system maintained by FINRA for equity securities that, among other things, are not listed on NASDAQ or any primary US national securities exchange.

On June 27, 2014, FINRA filed with the SEC proposed rule changes that would delete the FINRA Rule 6500 Series, which governs FINRA's operation of the OTCBB. On March 3, 2015, FINRA withdrew these proposed rule changes. Although the OTCBB.com website was shut down in November 2014 as part of the migration of FINRA's OTC Reporting Facility to a new platform, the OTC Bulletin Board remains in operation and information about the OTC Bulletin Board, including quotes and market statistics, can now be found on FINRA's website.

For further information on securities exchanges and trading markets, see Practice Note, Selecting a US Securities Exchange.