DEFINITION of K
K is a fifth letter added to a four-letter Nasdaq stock symbol indicating that the stock has no voting rights. The letter K is one of many fifth letters that denote something specific about the stock. To see the complete list, go to Investopedia's entry, "What are the fifth-letter identifiers on the Nasdaq?"
BREAKING DOWN K
There are currently few stocks with no voting rights in the market because investors tend to shun such assets. These stocks typically trade at a discount to their counterparts that do have voting rights for shareholders due to this loss of privilege. A shareholder vote is considered a fundamental right for investors. Without voting rights, shareholders generally feel that they are vulnerable to arbitrary or irrational business decisions by management. In cases where a lot of trust in placed in management because it has historically delivered significant shareholder value over a long stretch of time, shareholders do not mind holding "K" shares. LBTYK, the non-voting shares for Liberty Global PLC, is an example of a stock that has had longevity because of a single man, John Malone, a pioneer in the cable industry who has a faithful following of shareholders. No voting rights is not a problem for these shareholders because they believe in his decisions.
Perhaps shareholder sentiment about management is less clear, in which case a responsible firm would take action to eliminate a class of shares with no voting rights if it already had such a class. This occurred with Comcast Corporation, whose CEO, Brian Roberts, does not enjoy the same elevated status as John Malone in the cable industry. In December 2015 one share of CMCSK converted into one share of CMCSA, the stock issue with voting rights. Shareholders applauded this move.