AT&T (NYSE:T) didn't wait for the golden lasso of truth to reveal if a digital-first strategy is the right call for its WarnerMedia subsidiary. The movie studio's brazen decision to take its entire 2021 film slate and release it on its own HBO Max on the same day each film hits movie theaters is rattling two industries.

Multiplex operators traded as red as a movie house curtain on Wednesday. Shares of AMC Entertainment Holdings (NYSE:AMC) plummeted 16% for the day. Smaller rival Cinemark Holdings (NYSE:CNK) took a messier 22% drop. The thinking here, naturally, is that exhibitors as we know it are toast. It was one thing for AT&T's WarnerMedia to offer Wonder Woman 1984 as a one-off, hitting HBO Max later this month on the same Christmas Day as it hit the corner multiplex. Taking an entire year of movies and doing the same thing is a statement. Can movie theater chains survive this way until 2022?

Streaming services also took notice, but not to the same extreme as we saw with AMC and Cinemark. Netflix (NASDAQ:NFLX) slipped 1% on Wednesday, a modest retreat but notable on a day when all of the major market exchanges ticked higher. A stronger HBO Max means one more rival for Netflix to worry about, and this comes just as it's raising prices for its premium streaming platform. Lost in all of this is that shares of Roku (NASDAQ:ROKU) moved higher. The stock's 3% climb -- with AT&T rising a mere 0.5% -- made it Wednesday's surprising winner on the news. The future may get even better.

A woman on a couch with a remote control as she channel surfs.

Image source: Getty Images.

Plot twist  

Wall Street doesn't always get it right at first, and the entertainment industry's initial read on the news isn't kind to Roku. The thinking here is that AT&T now has more leverage over Roku in the HBO Max standoff. Roku users currently don't have access to HBO Max, only the original HBO streaming app. 

Roku operates its platform in a similar way to Apple's iconic App Store. Roku expects a cut of any new subscriptions that emerge from its platform and/or a share of the ad revenue. The mass appeal of Roku -- 46 million homes streaming an average of 3.5 hours a day -- has been irresistible to new services. It's telling that HBO Max and Peacock launched earlier this year without coming to terms with Roku. Both services launched with initially disappointing adoption rates. Peacock eventually came to terms with Roku. HBO Max playing nice with Roku may or may not happen before Christmas, but it doesn't make Roku a loser here.

AT&T had to gut most of the 2021 multiplex revenue out of its model -- taking AMC and Cinemark down with it -- because it's not on the country's most popular streaming hub with the most active viewers. Do you really think AT&T's WarnerMedia would be making this move if HBO Max was doing fine without a direct presence on Roku? The moral of the story here is clear. If you're a media stock with a nascent streaming service you will have to pay more than you think if you don't come to terms with Roku out of the gate.

HBO Max now has content, but it doesn't have leverage. It has a Ferrari, but it has to drive it in a school zone. It has a stocked pantry, but no one is coming over for dinner. What if Roku holds its ground? What if AT&T gambles away its 2021 theatrical release catalog and HBO Max doesn't get any closer to Netflix or any of the other more popular streaming services? It's AT&T -- not Roku -- that's sweating right now. It's Roku -- and not HBO Max -- that has the leverage now.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.