The Atacama Cosmology Telescope is a ground-based CMB survey that has mapped half the millimeter sky at significantly higher resolution and sensitivity than the Planck satellite. I will present new ACT results from a 9400 sq.deg. gravitational lensing mass map, including constraints on the amplitude of matter fluctuations as well as the Hubble constant at better than 2%, as well as bounds on the sum of neutrino masses and curvature density. With a consistent re-analysis of galaxy weak lensing from the DES, HSC and KiDS surveys, I will discuss these results in the context of the S8 tension. With an ACT lensing-informed measurement of the Hubble constant independent of the sound horizon, I will discuss implications for the Hubble tension.