OTC Bulletin Board (OTCBB) | FINRA.org, The OTC Bulletin Board (or OTCBB) is an interdealer quotation system that is used by FINRA members to make known to others their interest in transactions in any OTCBB eligible securities (as defined by FINRA Rule 6530), including offers to buy or sell at a stated price or otherwise, or invitations of offers to buy or sell.