Are public policies effective in enhancing gender balance in science, technology, engineering, and mathematics (STEM) graduate education? Although the literature is rich in studies that prescribe micro-level interventions to promote gender balance in specific STEM areas or institutions, there are surprisingly few studies that quantitatively evaluate existing macro-level policies. Using Germany's Excellence Initiative as an event study, I analyse changes in cohorts of doctorate recipients in STEM fields and investigate whether the Excellence Initiative's graduate school line of funding, which is a large-scale public policy that aimed to create and sustain STEM graduate programs, also succeeded to increase women's share among STEM doctorate recipients. Assessing difference-in-differences in natural sciences and mathematics doctorate recipients between 2000 and 2014, I find no statistically significant evidence that the Excellence Initiative led to any significant increase in women's participation in STEM studies beyond already existing trends in these fields. I find, however, significant differences between funded and non-funded STEM graduate programs in their rate of internationalization, which was another major policy target of the Excellence Initiative.