Sentence:  Since Rupert Murdoch famously bet the farm on Premier League football to rescue Sky TV in 1991, it has been the catnip that has <WSD>underpinned</WSD> subscriber loyalty and, even in a far more complicated media landscape, is seen as so vital as to be worth almost any price. 
Meaning of the word marked with <WSD> tags:  To give support to; to corroborate.