UPDATED, 1:08 PM: The U.S. stock market, including shares of media companies, continued to weaken as investors adjusted to life after Britain’s vote to leave the European Union.

Meric Greenbaum
Associated Press

The Dow Jones U.S. Media index closed down 3.6% to its lowest level since March. That was worse than the Dow Jones Industrial Average, which was down 3.4% and about even with the S&P 500, down 3.6%.

All Big Media companies lost ground. Fox ended down 7.7%, followed by Discovery (-7.2%), Viacom (-5.6%), Sony (-4.8%), Time Warner (-3.2%), CBS (-3.8%), Disney (-3.3%) and Comcast (-2.1%).

Elsewhere in media, those closing down more than 6% include Altice, News Corp and National CineMedia. Those between 5% and 6% include Time Inc, Dish Network, MSG Networks, Lionsgate, and Sinclair Broadcast Group.

Companies touching 52-week lows include AMC Networks, Liberty Media and New York Times.

PREVIOUSLY, 6:47 AM: Stocks for most media companies — especially those with extensive global operations — are reeling this morning following Britain’s surprising vote to leave the European Union.

Among Big Media, Discovery was hardest hit immediately after markets opened with shares off 5.3%. It was followed by Sony (-4.4%), Fox (-4.1%), CBS (-3.6%), Viacom (-3.3%), Time Warner (-2.9%), Disney (-2.7%), and Comcast (-1.9%)

Others battered include Altice (-9.6%), National CineMedia (-6.0%), and News Corp (-4.7%).

The Dow Jones U.S. Media Index is off 2.9%, ahead of the Dow Jones Industrial Average and Standard and Poor’s 500, both down 2.5%.

Virtually every company in the sector opened down on fears that the decision could further weaken currencies vs the U.S. dollar, and depress spending. Last year the value of the Euro dropped 16%, while the British Pound fell 7%, vs the U.S. dollar. That contributed to reductions in earnings guidance at Discovery, Fox, and Time Warner.

Discovery is especially vulnerable to a downturn in the British pound and the Euro following its acquisitions of Eurosport, SBS Nordic, and All3Media. About half of Discovery’s revenues come from overseas.

The vote “would potentially be a reason for bears/shorts to become incrementally negative especially as currency was a major headwind to reported Adj. EPS growth in 2015,” RBC Capital Markets’ Steven Cahall says.

But the company has hedged all of its Pound exposures, and 80% of its Euro exposures for 2016 — and much of 2017.

The company says it “respects the decision of the UK people in this historic vote to leave the European Union” and will “work closely with UK and EU leaders to successfully navigate this change and find new opportunities to shape our future.” Meanwhile, its hedges “will significantly minimize” any hit to Discovery’s financial performance “in the short-term and medium-term.”

Among other companies, Cahall says that a 10% drop in the value of the Pound could cut 1% from Fox’s pre-tax income — mostly by hitting the value of its 39% stake in Sky.

Others should only be nicked by such a currency change, Cahall says. Time Warner, which collects about 16% of its revenue from Europe, would only see a “modest impact.” Same with Viacom, which depends on Europe for about 17% of sales, especially from the UK’s Channel 5. Disney has “relatively limited exposure” with Europe accounting for about 12% of sales for the company’s cable networks, movies, and Euro Disney.

About 11% of Scripps Networks’ revenues come from overseas, especially Poland’s TVN.

And CBS collects about 2% of its revenues from the U.K. and 5% from the rest of Europe.

A British exit from the European Union could cut U.K. ad spending by about 70 million Pounds a year, ad firm Zenith estimated ahead of the vote. It added, though, that the effects would not be felt for months with firms it surveyed saying that they would not make immediate changes.

Even so, an exit would have a long term cost and “threaten to make cross-border accounts in Europe more costly and cumbersome to operate,” Zenith Head of Forecasting Jonathan Barnard said.