https://www.simonsfoundation.org/mathematics-physical-sciences/simons-investigators/ states:

Each year, the Simons Foundation invites nominations from universities in the United States, Canada, the United Kingdom and Ireland for the Simons Investigators in Mathematics, Physics, Astrophysics, Theoretical Computer Science, Mathematical Modeling of Living Systems (MMLS), and Math+X Investigators programs. A Simons Investigator is appointed for an initial period of five years. An Investigator will receive research support of $100,000 per year.