Warner Bros. At the same time, this short-term move roughly doubled Warner Bros. Discovery one-year gain to 136%, with the stock closing Sept. 30 at $19.53, close to its 52-week high of $20.24. Beyond the takeover buzz that's likely helped drive the stock up, there's still the reality that Warner Bros. Add in the 100% tariff on foreign-made films that was just proposed by President Donald Trump, and the business climate for Warner Bros.