Samsung Electronics shares plunged during trading Monday as the company's plan to allocate up to 110 trillion won ($79 billion) for shareholder returns fell short of market expectations. Samsung Electronics shares were trading at 257,000 won, down 8.7 percent from the previous session, as of 2 p.m., according to the Korea Exchange. Its preferred shares fell 7.83 percent. The chipmaker's plunge sent other Samsung Group affiliates reeling. Samsung C&T fell 7.84 percent while Samsung Life Insurance