The quantitative requirements are quite similar to an econ phd.
Math stats & probability (through math department, usually two courses)
Real analysis (sometimes called advanced calc)
Ordinary Differential equations
Those are sufficient for most cases. You can take more advanced courses like measure theory and topology (I never took these, but I know the concepts would have helped with micro and econometrics), but they aren't as common.
Asking this on the econ subforum can may be useful.