Let's assume the 1-year government bond yield is at 5% (it's not, but it simplifies the math, so bear with me). As a gross oversimplification, that means that a $20 investment today will produce a risk-free return of 5% ($1) at the end of a year. The converse is also true: if a risk-free investment produces $1 in revenues over the course of a year, then the investment should be valued at $20.