NEW YORK (TheStreet) -- Despite the appearance this year of a team-up between an activist investor and a strategic acquirer in dealmaking, don't expect a repeat.

The combination of Pershing Square Capital Management with Valeant Pharmaceuticals (VRX) to pursue Allergan (AGN) "may have been a one-time opportunity," said Paul Parker, co-chair of global mergers and acquisitions at Goldman Sachs (GS) , at The Deal Economy event on Thursday at Nasdaq.

Parker, a former global head of M&A at Barclays, joined Goldman Sachs in August. While at Barclays, Parker advised Valeant on the Allergan hostile bid.

Actavis ACT said last month it would acquire Allergan for $219 per share in a $66 billion deal.

Parker, interviewed onstage by Jeffrey Kanige, editor in chief of The Deal, noted there has been debate on the legality of arrangements such as the Pershing Square-Valeant one.

"That remains an open debate," he said.

"The other question is, if you bring an activist to help you buy a company, you end up with an activist in your company," Parker continued. "Not everybody likes to have that on the back end of a transaction."

The keynote conversation also included Parker's views on the cable industry, M&A abroad and inversions.

Parker, who advised Comcast (CMCSA) on its proposed purchase of Time Warner Cable (TWC) , said he expects to see more cable industry consolidation.

"We're in the last innings of consolidation" in the cable space, he said.

As for inversions, Parker said he hasn't seen a single transaction where people have used taxes as the No. 1 strategic reason. He also said inversions "have not gone away."

"The framework for them has changed meaningfully. That said, the majority of them stay and are either close or heading to closing," Parker said.

Asked about his M&A outlook, Parker said that looking at the technicals and fundamentals, "nothing stands out in my mind that will derail that."

--Written by Armie Margaret Lee in New York

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