According to stockholder reports there is no ‘apparently’.
They simply exchanged ownership of enough shares to qualify for the board of directors of newscorp for enough shares to qualify for the board of 21st century fox:
“In a sign the Saudis are keeping faith in Mr Murdoch’s more modern cable, television and film assets, the Kingdom has retained its 6.6 per cent holding in Twenty-First Century Fox, worth about $US1.7 billion.”
And 21st Fox is heavily invested in the Saudi’s companies as well:
“Twenty-First Century Fox owns a 19 per cent stake in Rotana Group, an entity the Prince owns separately from Kingdom Holding.”