Elon Musk, the world’s only trillionaire, has quietly become the biggest known donor in this year’s midterm elections, doling out more than US$276 million since July to try to save Republican majorities in Congress. The numbers, first reported by the New York Times ahead of this week’s federal filing deadline, were confirmed by Andrew Romeo, a spokesman for Musk’s super PAC (Political Action Committee). The money includes US$158 million given to the Senate Leadership Fund, the main super PAC...