The co-founder and current board member of Twitter, Ev Williams, said today that he plans to sell a "minority of [his] TWTR" stock over the next year , and doesn't plan to sell "more than 30 percent" of his holdings. Williams is the company's largest individual shareholder, so his recent announcement may make some investors worried. However, Twitter stock was only down less than 1 percent Thursday following this news. Recode reports: