Should eco-conscious investors support a company that’s developing innovative solutions to climate change—even if that company is also a major polluter? The market’s answer to this question has been a resounding “no,” as evidenced by the investment policies that exclude traditional oil producers from most so-called sustainable funds. But this stance eliminates some of the most prolific and influential producers of green innovation, including Exxon Mobil, BP, and Chevron, according to recent research by Harvard Business School Professor Lauren Cohen. Faced with mounting concerns about climate change, oil companies are diversifying their businesses, putting money toward renewable energy sources and green technology. While sustainable funds shun fossil fuel producers, which contribute half of the world’s greenhouse gases, Cohen’s study suggests that these companies could also play a key role in stemming the damage.