PARIS — Media and entertainment conglomerate Vivendi SA is nearing a decision on whether to sell its stake in NBC Universal and clear the way for the creation of one of the most powerful media companies in the world.

The French company’s finance chief told an investors conference in Barcelona that Vivendi’s board still has three weeks to decide whether to sell its 20 percent stake in NBC Universal. That is a necessary step before the unit’s other shareholder — General Electric Co. — can move forward with a plan to sell a majority stake to U.S. cable TV operator Comcast Corp.