The answer? Natural resources, land rights, and stocks, all invested in mutual funds and limited partnerships.
We got a lot of requests to do the same thing to Barack Obama, and for him the answer is much easier.
First of all, Obama has released copies of his tax returns, so we're able to produce hard numbers when it comes to what he makes.
Second, his investment strategies are much more coherent than Ryan's. Obama made his fortune from a few sources, and has it invested and stored in a few surprising — but also easy to track — ways.
We got the information from personal finance disclosures and released tax returns hosted by the Center for Responsive Politics.