Media companies, already jolted by sweeping changes in how people watch video and read print, now will have to tangle with the changes wrought by the election of Donald Trump as the 45th president of the U.S.

Television and film stocks led by Disney (DIS) , 21st Century Fox (FOXA) and CBS (CBS) were trading lower on Wednesday amid concerns that marketers could cut back on spending and that changes in trade and foreign relations could upend the global economy, cutting demand for media offerings.

Furthermore, regulators in a Trump administration may be less likely to approve large-scale mergers such as AT&T's (T) agreement last month to acquire Time Warner (TWX) in a cash-and-stock deal valued at $85 billion. The Department of Justice also has yet to rule on Lions Gate Entertainment's (LGF) acquisition of Starz (STRZA) , a $4.4 billion deal announced in June.

By comparison, the Obama administration approved Comcast's (CMCSA) acquisition of NBCUniversal and Charter Comunications' (CHTR) buyout of Time Warner Cable.

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"No one knows what will happen to the AT&T-Time Warner merger because it's a completely different world altogether than the one that approved Comcast buying NBCUniversal," said Shahid Khan, founder of New York media industry software and data provider Mediamorph. "Whether they get approved or not is all up in the air."

Throughout the campaign, Trump sparred with a variety of media outlets, CNN and Fox News as well as The Washington Post and Univision Communications, charging them with being unfair toward his campaign. At a campaign rally in Gettysburg, Pa., on Oct. 22, Trump said that "AT&T is buying Time Warner, and thus CNN, a deal we will not approve in my administration because it's too much concentration of power in the hands of too few." 

Potentially more sweeping for media companies is the notion that spending on advertising for television and print could slide if uncertainties about Trump's fiscal and trade policy destabilize the U.S. economy. 

"There will be a major reassessment of marketing commitments," said Peter Kreisky, a longtime consultant to media companies in New York. "There will be a great hesitancy on the part of advertisers to commit to major expenditures until they see what happens to the economy. If we head straight into a recession, clearly that will have a big impact on advertisers."

A slowdown in advertising both at the network level and at news operations such as CNN and Fox News could adversely affect both companies considering that the news operations were bolstered by ad sales over the past 18 months. Record advertising at CNN helped to fuel Time Warner's overall 2% gain in ad sales in the third quarter.

"If I'm a TV network, I'd be really concerned right now," Khan added. "They'll need to start exploring other businesses and reinventing who they are and what they stand for."

Media companies also could be jolted by a slowdown in the global economy. During the campaign, the Republican nominee made clear his opposition to international trade deals while offering few specifics about how he would accelerate a slow but gradual U.S. economic recovery.  

Disney, Fox and Time Warner have extensive holdings overseas and view growth in Asia and Latin America as central to their business strategies, given slower growth for cable TV and the uncertain future for subscription-based multichannel platforms such as Dish Networks' (DISH) SlingTV and AT&T's DirecTV Now, expected to launch later this year.

Questions abound as to the effect an uncertain economic future could have on the subscription-based streaming services that media companies are betting can help to offset the slow of decline in the number of cable TV customers. Both Netflix (NFLX) and Time Warner, which relies in part on HBO for growth, were falling.

In contrast, cable and satellite TV providers Dish, Comcast and Charter all were up Wednesday afternoon, as were AT&T and Verizon Communications (VZ) .

"If we head straight into a recession, clearly that will have a big impact on advertisers," Kreisky added. "I anticipate that we'll have a recession at some point in the next 18 months, and all marketing companies are going to be reassessing where they put their bucks."

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