A team associated with Manifold Markets has created a prototype market for minting and trading impact certificates.
To help test it out, I'm sponsoring a $20,000 grants round, restricted to forecasting-related projects only (to keep it small - sorry, everyone else). You can read the details at the Astral Codex Ten post. If you have a forecasting-related project idea for less than that amount of money, consider reading the post and creating a Manifund account and minting an impact certificate for it.
If you're an accredited investor, you can buy and sell impact certificates. Read the post, create a Manifund account, send them enough financial information to confirm your accreditation, and start buying and selling.
If you have a non-forecasting related project, you can try using the platform, but you won't be eligible for this grants round and you'll have to find your own oracular funding. We wouldn't recommend this unless you know exactly what you're doing.