SEOUL (Reuters) - Samsung Electronics Co Ltd <005930.KS> shares opened sharply lower on Tuesday, as the firm's decision to halt sales and exchanges of the Galaxy Note 7 smartphone weighed on sentiment.

Samsung shares fell as much as 5 percent to 1.596 million won ($1,431.71), their lowest since Sept. 30. Shares were down 4.2 percent as of 0006 GMT, underperforming the broader market <.KS11> that was down 0.1 percent.

(Reporting by Se Young Lee; Editing by Stephen Coates)