Stocks that trade on the OTCBB, will have the suffix ".OB".
It is important to note that companies listed on the OTCBB are not a part of the Nasdaq Exchange. The truth is, OTCBB stocks are not especially large or stable and are considered very risky. As a result, very few OTCBB stocks are successful in making the jump from this market to the Nasdaq or any other major exchange because they are unable to meet the listing requirements. Furthermore, because OTCBB stocks tend to trade infrequently, the bid-ask spread is larger.
Investment dictionary. Academic. 2012.