There are approximately 15 female mathematicians who hold a permanent position in a Swiss research university (from lecturer to professor level). There are many more post-doctoral researchers and doctoral students. There are no specific activities organized for female mathematicians in Switzerland, nor is there an organization whose membership is defined by this common attribute.
The Swiss National Science Foundation has a funding program and various policies aimed at encouraging and assisting female researchers, see for example here.
On the occasion of the 100th anniversary of the Swiss mathematical Society, Christine Riedtmann wrote an informative article about the history of women mathematicians in Switzerland (in German) which can be found here.