UPDATE, MONDAY 1:55 AM PT: Following yesterday’s news that Sophie Turner Laing is primed to be CEO of the proposed Shine, Endemol and Core mega-indie, Shine Group CEO Alex Mahon has confirmed she will leave the company. The move was expected, and the exec has announced her departure to staff internally. Mahon will remain through the transition period with insiders suggesting she will be aboard for a few months before moving on. She joined Shine in 2006, originally as Managing Director of Shine TV, and later became COO Shine Group before being elevated to CEO in September 2012. Prior to Shine, Mahon was COO at UK producer talkbackTHAMES and Director of Commercial Development and Strategy at FremantleMedia.

PREVIOUS, SUNDAY 2:25 PM PT: The executive structure of the proposed merger of Shine, Endemol and CORE Media continues to come into sharper focus with confirmation that a combined group would be led by former top BSkyB executive Sophie Turner Laing.

21st Century Fox and private-equity firm Apollo Global Management are behind the merger plan that would create the world’s biggest independent production company working across scripted and non-scripted television.

A spokesperson for the pair of companies said today, “Pending the parties finalizing an agreement to form a joint venture comprised of Endemol, Shine Group and CORE Media Group, the venture partners today confirmed that Sophie Turner Laing, former Managing Director of Content at BSkyB, would become the new venture’s CEO.”

Further, under the proposed scenario, Endemol CEO Just Spee and Shine Group CEO Alex Mahon would remain with their respective companies following the close of the transaction, working with Laing on the transition and integration of the business operations. Word in industry circles, however, is that the executives will leave once the transition is completed.

The first major executive move towards clarifying the new structure came three weeks ago when Core Media Group president Marc Graboff exited his post as the company’s operations were absorbed into Endemol North America under Cris Abrego and Charlie Corwin. At that time, it also became clear that neither Endemol’s Spee not Shine’s Mahon would get the top post at the new company, with attention focusing on Turner Laing, who had been linked to the new venture.

The proposed Shine-Endemol-Core venture was first proposed in mid-May, a few weeks before Turner Laing announced she was stepping down from her position as Managing Director of Content at the 21st Century Fox-controlled BSkyB. She had been with Sky for 11 years and led the expansion of its portfolio of entertainment channels, with the launch of Sky Atlantic, Sky Living and Sky Arts during her tenure. She also was instrumental in Sky’s partnership with HBO and key to Sky’s overall commitment to spending an annual £600M on original British programming. At the time of the departure announcement, BSkyB Chief Executive Jeremy Darroch said, “I am pleased that she will continue to have a close relationship with Sky in the future.”

The next big shakeup in the merger process is how the operations of Endemol North America and Shine America would be integrated. Endemol may be the stronger of the two entities, though combining them will likely not be as clear-cut as the folding of Core into Endemol. Shine America CEO Rich Ross is considered a solid executive.

The company’s flagship brands on the non-scripted side include MasterChef and The Biggest Loser. It is also strong internationally, owning 26 production companies across 11 countries. Of utmost interest to 21st Century Fox is believed to be Endemol’s global footprint: it owns 90 companies in more than 30 countries, which would create a tidy supply chain for Fox International Channels.

The whole endeavor is part of continued M&A fever that’s crossing oceans and zig-zagging the globe as the importance of scale intensifies. Myriad companies – big and small — have been acquired by the likes of Warner Bros, ITV, Sony and Red Arrow over the past two years, with Liberty Global and Discovery just this week completing their £550M deal for All3Media.