Cascade Investments, the secretive private equity vehicle of Microsoft chairman Bill Gates, has joined the consortium bidding for Univision, the US Spanish language broadcaster.

Grupo Televisa, the Mexican broadcaster leading the bid, said in a regulatory filing to the Securities and Exchanges Commission that it had "decided to work together with" US buy-out firms Bain Capital, The Blackstone Group, Carlyle Group, Kohlberg Kravis Roberts as well as Cascade.