Elon Musk's groupies are making the right call for the wrong reasons. Shares in Tesla, where he is chief executive, and SolarCity, where he is chairman, are at multi-year lows as investors question their giddiness about far-off profit. It makes sense for two overvalued companies. But both may be more insulated against the plummeting oil price that helped prompt the rethink than owners give them credit for.
The two companies can legitimately claim to be disrupting established industries. Tesla's upcoming Model 3, due out next year, will be the key test for whether the company can morph from a niche manufacturer of expensive curiosities into a mass-market producer of affordable battery-powered vehicles.