NBC News' announcement that popular anchor Megyn Kelly will be leaving Fox News didn't prompt investors to sell shares in 21st Century Fox (FOXA) .

Fox shares rose 2.4% Tuesday to $28.72, outpacing a broad market rally that added a comfortable 0.9% to the S&P 500 index.

Resiliency in Fox shares was due in part to investor appreciation that the departure of one anchor isn't likely to have a sharp negative impact on Fox News' ratings nor its ability to sell advertising. Additionally, Fox's cable TV networks, which also include FX, the National Geographic Channel, Fox Sports 1 and the YES Network, have been on fire.

Revenue at Fox's cable TV group jumped 10% in the third quarter to $3.81 billion, as profit rose to $1.38 billion from $1.31 billion a year earlier. Net income totaled 51 cents per share for the three-month period, more than exceeding a consensus analyst forecast that had predicted 44 cents a share.

Fox's better-than-expected performance, which appears to have continued into the fourth quarter, was due in no small part to ratings at Fox News. The conservative-leaning news network averaged 2.4 million viewers during prime time hours last year and 1.4 million daily, making the network the country's most-watched cable TV channel in 2016, beating perennial winner ESPN,

For those watching Fox shares, the stock is comparatively undervalued. Fox trades at a multiple of 15.4 times earnings, trailing the figures of rivals Time Warner (TWX) , CBS (CBS - Get Report) and Disney (DIS - Get Report) , parent of ESPN, according to Bloomberg data.

"The ratings have been very good, and the valuation gap with the rest of the group is unwarranted," said Wells Fargo media analyst Marci Ryvicker, who upgraded Fox shares on Tuesday to the equivalent of a buy.

And for investors wary about Rupert Murdoch's propensity to make budget-stretching acquisitions, the company's announcement last month that it aims to spend $14.2 billion to acquire all of London satellite and internet provider Sky  -- well, it's unlikely Fox has any more leeway to buy anything else.

"The big fear was that they would go on some M&A spree, and now that they're going to buy Sky, they don't have the capacity to buy anything else," Ryvicker added. "And that's a positive."

Also working in Fox's favor is the carriage agreement it has signed with Comcast, made public over the weekend. The multichannel deal locks in a four-year revenue stream for Fox's cable TV network group and also ends the 15-month blackout of its YES Network, the largest regional sports network in the country, which also broadcasts the Brooklyn Nets, among other live sporting events.

While Fox News is sure to be closely watched in the coming months for signs of weaker ratings after Kelly's exit, the network has built up a loyal following, predominantly of older, white, conservative men, during its 20 years of existence. And while Kelly, 46, might be called Fox News' rising star, its most popular anchor remains Bill O'Reilly, 67. The network also retains popular anchors Sean Hannity, 55, and Tucker Carlson, 47.

Kelly, whose contract runs through July, will host her final show as a Fox News anchor on Friday,  a source close to the matter said.