Simons Foundation: Simons Collaborations in Mathematics and the Physical Sciences

Aim: to stimulate progress on fundamental scientific questions of major importance in mathematics, theoretical physics, and theoretical computer science. Funding: up to $2.5 million for 4 years. Please note: The collaboration director should hold a faculty, or equivalent, position at a U.S. or Canadian institution with a Ph.D. program

https://www.simonsfoundation.org/funding/funding-opportunities/mathematics-physical-sciences/simons-collaborations-in-mathematics-and-the-physical-sciences/