Michael Angelakis, 50, the Comcast Corp. executive who headed the negotiations for NBCUniversal and Time Warner Cable Inc., will resign his posts as chief financial officer and vice chairman to lead a new Comcast-controlled $4.1 billion investment arm.

The new venture, which Comcast calls a "strategic company," would be one of the biggest funds of its kind in Pennsylvania and will be looking for high-return investments like one Comcast made into the TV shopping network QVC.

Comcast put $300 million into QVC, based in Chester County, in the mid-1980s and sold it for $7.9 billion in 2003.

The new role for Angelakis, Comcast's second-ranking executive, comes at a sensitive time for the cable giant. Its proposed $45 billion acquisition of Time Warner Cable Inc., a transaction negotiated by Angelakis, is still under exhaustive regulatory review by the Federal Communications Commission and the Justice Department.

Comcast - which had expected to complete the Time Warner Cable deal by now - said Angelakis would stay on as chief financial officer through a closing that could happen this summer if the federal government approves it. He also is expected to help transition to a new CFO.

Comcast had to disclose the pending top-level executive change now because it will begin searching for a new CFO.

Howard Fisher Associates, a specialized search firm with offices near the Comcast Center, will look for Angelakis' replacement - who is likely to be among the best-paid CFOs in the nation.

Brian Roberts, Comcast chairman and chief executive officer who has been quoted saying, "I would like Michael to be CFO forever," said that the integration and merger plans for Comcast and Time Warner Cable were well-advanced and "Michael is really ready and excited to turn his attention to the next phase of his career and relationship with Comcast."

Roberts has called Angelakis a "rock star" for his investment skills and said that he has had "an incredible track record in making money."

The Wall Street Journal recently named Angelakis one of the nation's top CFOs.

Angelakis declined to comment.

"Comcast is losing an extraordinarily talented CFO," telecommunications analyst Craig Moffett said Tuesday. "Over his eight-year tenure, he has seen the stock triple, in no small measure due to his brilliant stewardship."

Angelakis engineered the two-step $30 billion acquisition of NBCUniversal in which Comcast bought 51 percent of the New York entertainment company. Comcast partly financed the purchase of the other 49 percent with NBCUniversal's profits.

The Time Warner Cable deal is another highly complex transaction involving a stock purchase of Time Warner Cable, an exchange of cable assets with Charter Communications Inc., a sale of cable assets to Charter, and a spin-off of some of Comcast's cable assets into a separate, publicly traded company.

Moffett added: "This is an incredible opportunity for Michael to write his next chapter. And Comcast is giving him a tremendous vote of confidence by investing alongside him."

Comcast will make available $4 billion for the new investment company and Angelakis will put $40 million of his personal funds into the new company that will invest in and operate growth companies. Angelakis will be the venture's chief executive officer and recruit managers who also will likely put in their own money.

Angelakis had worked as a top executive for the private equity firm Providence Equity Partners before being recruited to Comcast in 2007.

The new Angelakis-headed company will be similar to a private equity fund, but it won't flip companies for fast returns or be forced to raise money from investors, because it will tap Comcast's funds.

Ira Lubert, cofounder at Independence Capital Partners, a Philadelphia-based group of real estate, private equity, and venture capital funds, said that the Angelakis-headed company - if considered a private equity fund - "would be the largest private equity fund ever in Pennsylvania."

Angelakis can invest Comcast's $4 billion as he and his management team see fit, though they will need Comcast's approval for investments of more than $400 million.

This new company also will not replace Comcast Ventures, which seeds early-stage start-up companies with $2 million to $15 million and has offices in San Francisco, New York, and Philadelphia.

The Angelakis-headed company is expected to make larger investments into media, advertising, or technology companies. Angelakis is expected to have wide latitude to find investments that meet his criteria.

The new Angelakis company will launch this year or in early 2016, according to a filing with the Securities and Exchange Commission.

Angelakis will be paid $100,000 a year as a senior adviser to Comcast after his resignation as CFO and vice chairman and compensated $8 million a year as chief executive officer of the new company.

Angelakis was paid $19.2 million as CFO and vice chairman in 2013, according to the company's SEC filing.

"As we enter the final phase of the Time Warner Cable transaction," Angelakis said in a statement Tuesday, "this is a great time to begin a transition and I am excited to start this new, entrepreneurial company."

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Inquirer staff writer Joseph N. DiStefano contributed to this article.