19c3 stock includes any stock listed on an equity exchange after April 26, 1979. The classification of a 19c3 stock refers to the rule enacted by the Securities and Exchange Commission (SEC), i.e., the SEC rule 19c3 which allowed off-board transactions to be made. Such a classification enabled members of exchanges to trade these stocks off the board. Before April 26, 1979, members of the major exchanges had to be physically present at an exchange in order to conduct stock trades. This meant that Over-the-Counter (OTC) trades could not have legally occurred.