As I understand it, there are two main ways to invest in fossil fuels - stocks & bonds. Buying stocks in fossil fuel companies doesn't finance their continued o

As I understand it, there are two main ways to invest in fossil fuels - stocks & bonds. Buying stocks in fossil fuel companies doesn't finance their continued operation, so probably not much point taxing those. But buying bonds from a fossil fuel company is directly funding their operation, so I would assume this is where the theoretical tax would be applied?