Yahoo ! has taken the unusual step of cancelling the conference call following its earnings announcement on Tuesday. Public companies usually announce their results and then stage a conference call in which senior executives deliver set pieces before taking questions from financial analysts, institutional investors and, sometimes, from media too. The question and answer sessions are seen as an important accountability mechanism and can sometimes become rather tetchy if executives can't deliver convincing answers. It's entirely conceivable a Q&A with Yahoo ! could become heated as the company fends off critics of its colossal security SNAFU and allegations it provided US authorities with a backdoor. Those messes have led to suggestions that Verizon, which has promised to acquire the Purple Palace, might either walk away or seek a lower price as the portal arguable has less value now than when the acquisition deal was done.