The PE firm, Siris Capital Group, offered $12.50 per share in cash for Polycom, representing a premium of 15% to Polycom's Thursday close. Polycom's shares rose about 13.6% to $12.35 in premarket trading on Friday, just shy of the offer price. Mitel shares jumped 22%. The deal could be a setback for activist investor Elliott Management, which disclosed stakes in both companies last October and subsequently championed a deal between the two. Mitel said in April it would buy Polycom for about $1.96 billion in cash and stock. Mitel said on Friday it would not raise its offer for Polycom and waived its right to match Siris' offer. As a result, San Jose, California-based Polycom will pay Mitel a termination fee of $60 million.