A small change could have a big impact.

Tesla can now set standing voting instructions for retail shareholders. The shareholders will automatically vote with the Board of Directors' recommendations. Of course, any shareholder can override the preset votes.

There are a few reasons Tesla might have made the change.

For starters, it makes it easier to marshal the auto maker's huge retail shareholder base. Smaller retail investors hold roughly 40% of the stock available to trade, about twice the level of other large tech stocks, according to Bloomberg.

And marshaling those shareholders makes it easier to pass board-approved recommendations. That can matter since institutional proxy advisors don't always side with the board. Both ISS and Glass Lewis recommended shareholders vote against Elon Musk's potential trillion-dollar 2025 incentive plan.

And board-favorable shareholder voting makes it ever-so-more-likely that Tesla and SpaceX merge. Many investors and analysts believe a Tesla-SpaceX merger is inevitable.

Most also see an all-stock deal with SpaceX paying a premium. Any deal would require a shareholder vote. Musk essentially fully controls SpaceX-no vote needed-but Tesla shareholders would still have to sign off.

Tesla and SpaceX didn't respond to requests for comment about the voting changes.

To be sure, shareholders don't know if or when a merger will happen. It might not. Wall Street has good reasons for suspecting one, though: Elon Musk runs both companies and both firms are all about AI.

SpaceX runs AI data centers, and Tesla uses AI to train robo-taxis and humanoid robots. The companies are also collaborating on AI applications and building a semiconductor facility to help remove any bottlenecks to AI growth.

The change wasn't doing much to the stocks in premarket trading. SpaceX was up 0.2% at $149.59, and Tesla was down 0.8% at $350.10. The S&P 500 and Dow Jones Industrial Average futures were up about 0.1%.