Ciena Corp will buy Nortel Networks Corp's optical networking and carrier ethernet business for $769 million after outbidding Nokia Siemens Networks in a three-day auction, sources told Reuters on Sunday.

Ciena's winning offer consists of $530 million in cash and $239 million in convertible notes, one of the sources said, speaking on condition of anonymity since details of the auction have not been made public.

Last month, the U.S. network equipment maker announced that it had made a 'stalking-horse' offer for these assets of Nortel, the Canada-based telecommunications company that filed for bankruptcy in January and has been auctioning off assets.

Ciena initially offered $390 million in cash and 10 million shares of Ciena stock, for a total deal value of $522 million, based on the Friday closing price of Ciena stock.

The final bid by Nokia Siemens Networks, which had teamed with private equity firm One Equity Partners, came very close to Ciena's offer, the source said.

(Reporting by Anupreeta Das; Editing by Lincoln Feast)

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