Early SpaceX Investor Says Tesla Tie-Up Is Only a Matter of When

A post-IPO merger between SpaceX and Tesla Inc. is inevitable and only a question of timing, because Elon Musk will want to consolidate control across his companies, according to early SpaceX investor Peter Diamandis.

The combination makes sense because it would give Musk the super voting rights he has at Space Exploration Technologies Corp. — where he had 85.1% control before the filing for an initial public offering — but lacks at publicly held Tesla, Diamandis said Wednesday in a Bloomberg Television interview.

“I put it not as a matter of if but only a ...