Fox Corp., led by CEO and executive chairman Lachlan Murdoch, on Wednesday reported sharply higher second-quarter earnings on valuation changes and higher advertising revenue.Fox — which, after Rupert Murdoch agreed to sell most of 21st Century Fox to Walt Disney for $71 billion, became a stand-alone company mostly focused on news and sports — reported net income of $314 million for the latest quarter, or 48 cents per share, compared with $24 million in the year-ago period, or 1 cents a