Investing guru Mario Gabelli said he has a “simple concept” in his approach of just which media stocks to buy.

Gabelli, the CEO of GAMCO, reportedly likes companies that are controlling the content of movies and videos, and even those that control the music libraries that millions of users are playing on their mobile devices.

CNBC.com explained that means stocks like Vivendi, Sony and Viacom, which he thinks could improve its position by selling non-U.S. assets and reducing its debt obligation.

"I have a simple concept," Gabelli said at this week’s Yahoo Finance All Markets Summit. "Whatever you see on any device anywhere in the world, you follow it both on content and creativity," he said.

He applauded the Trump administration's quest to eliminate excessive business regulations imposed under President Barack Obama, although he wasn’t fond of Trump’s common Twitter usage.

"We still have a democracy," Gabelli said. "The tweeting is not necessarily the way to do it. I don't like the tactics we're using, but I do like the approach."

To be sure, investors are increasingly pricing in the effect of a corporate tax cut into the shares of U.S. companies, leaving the market primed for a steep selloff if the Republican-controlled Congress fails to pass one of President Donald Trump's top priorities.

The benchmark S&P 500 is up nearly 6 percent from its August lows as the Trump administration has rolled out its tax reform proposal, which would cut corporate taxes to 20 percent from the current 35 percent and allow companies to bring back some of the $2.6 trillion in cash currently held offshore at reduced rates, Reuters reported.

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