The media and technology company is led by Barry Diller and has been welcomed as a significant investor by those at MGM Resorts.
The operator’s potential for digitalization, with its joint partnership with GVC Holdings (Roar Digital) expanding on the US sports betting scene, was a key part of what attracted IAC.
MGM Resorts CEO and President Bill Hornbuckle said: "IAC's expertise in growing and expanding brands online is a natural fit for our focus on enhancing the resort experience through curated and personalized offerings, as well as digital enhancements in sports betting and online gaming."
With MGM Resorts shares closing on Friday at $19.03, stocks were up 14%, to as high as $21.81, after the announcement.
Diller, Chairman and Senior Executive of IAC, said: "What initially attracted us to MGM, besides its leadership in leisure, hospitality and gaming, was an area that currently comprises a tiny portion of its revenue – online gaming.
"IAC's foundational concept of seeking opportunities to build interactive businesses is our base rationale – there is a digital-first opportunity within MGM Resorts' already impressive offline businesses; and with our experience we hope we can strongly contribute to the growth of online gaming."