Microsoft Corp. on Friday declined to comment on mounting speculation by traders that the world's largest software company was set to issue a profit warning.

``We never comment on rumors or speculation and we certainly don't comment on this kind of trader speculation,'' Mark Murray, a Microsoft spokesman in Redmond, Wash., told Reuters. 

Shares of Microsoft traded at $67 on Instinet, down from a Thursday close of $68.90. 

Also on Friday, telecommunications equipment giant Nortel Networks Corp., in a shock warning to financial markets, announced new job cuts and a $2 billion financing deal and predicted a big second-quarter loss.