In the second major broadcast-legacy media mashup deal of the week, Rupert Murdoch’s 21st Century Fox has taken a majority stake in National Geographic Society’s media assets, including National Geographic magazine, in a deal valued at $725 million.

21st Century Fox already had an 18-year partnership with National Geographic to run the Society’s cable TV channels. This deal expands that partnership, giving 21st Century Fox a 73 percent stake in a new entity called National Geographic Partners, which will include the cable channels, the magazine brands, the digital and video assets, and all the ancillary media business such as ecommerce, licensing, events and archive sales.

The news comes a day after Meredith Corp.’s announcement that Media General bought it for $2.4 billion in a deal that also combines TV assets with magazine and digital media.

National Geographic chief media officer Declan Moore will become CEO of National Geographic Partners.

The deal essentially separates the media assets from the Society’s missions of exploration, science and education, but allows for a continued revenue stream to help support those efforts. Meanwhile, the purchase price significantly boosts The National Geographic Society’s endowment to almost $1 billion.

A shared governance structure will be put into place, with equal representation from each company on the board. The board chair will alternate annually. National Geographic Society president and CEO Gary Knell will serve as the board’s first chairman.

“We’re working hard to focus our portfolio on brands that have unquestionable consumer appeal,” said 21st Century Fox CEO Rupert Murdoch in a statement. “This expanded partnership, bringing together all of the media and consumer activities under the National Geographic umbrella, one of the most treasured names in the world, creates vast opportunities and enables this business to be even more successful in a digital environment.”

The deal is expected to close by the end of the year.