21st Century Fox already owns 39 percent of Sky, and media mogul Rupert Murdoch has attempted to buy the remaining share before. That takeover bid was dismantled, however, once the company -- then called News Corporation -- was caught up in a huge phone hacking scandal. If the two were to merge, it would give Murdoch enormous influence over the news and media industries. Sky is a huge telecoms player and pay-TV provider in the UK, with a range of mobile, broadband and satellite TV packages. The broadcaster also runs Sky News, a prominent online and TV news organisation. Critics argue the deal would give Murdoch too much power, given he also controls The Times, The Sunday Times and The Sun.

Ofcom's investigation will also examine whether Sky's suitor is "fit and proper" to own a broadcast licence. It's a separate legal process required under the UK's Communication Act, and will no doubt examine Fox's business practices, past and present. In a statement, the company said: