After three years of negotiations, CBS and Viacom are coming together to form a $30 billion company, controlled by Shari Redstone and cementing her status as possibly the most influential woman in media.

The merger comes at a time when upheaval in the traditional pay-TV market and the rise of digital streaming services have changed the economics of the entertainment industry and pressured media companies to either grow or sell themselves off. With streaming video companies like Netflix now the leading story, CBS and Viacom are fusing their war chests to better compete in the rapidly morphing world of TV and film watching.

But the combined company will still be far smaller than many of the media titans that it will need to compete with.