Elon Musk's most successful companies, Tesla and SpaceX, are having very different years in 2018. SpaceX debuted a powerful new rocket, the Falcon Heavy, and has successfully launched seven orbital missions. Tesla has struggled to produce its Model 3 electric sedan at promised rates, raising questions about the company's cash flow and encouraging short-sellers. On...

Elon Musk's most successful companies, Tesla and SpaceX, are having very different years in 2018. SpaceX debuted a powerful new rocket, the Falcon Heavy, and has successfully launched seven orbital missions. Tesla has struggled to produce its Model 3 electric sedan at promised rates, raising questions about the company's cash flow and encouraging short-sellers. On...