As SpaceX moves toward its IPO, a growing number of sustainability-focused fund managers are flagging concerns over the unprecedented degree of control Elon Musk would hold over the company. Our own Marcela Pinilla told Bloomberg the governance structure is "too, too risky" for the kind of long-term company stability investors should look for. Here's why concentrated control at this scale matters to long-term investors — and what we're watching as the IPO unfolds.