Where exactly are my 3a assets located?

You pay your money into the findependent 3a retirement savings foundation. This is a foundation under Swiss law, legally separate from Findependent AG, which is supervised by the BVG and Foundation Supervisory Authority of the Canton of Aargau (BVSA). The cash is parked in the retirement savings foundation's collective account at Hypothekarbank Lenzburg, while Zürcher Kantonalbank (ZKB) acts as a reliable custodian bank for your securities in the background. In short: Your money is stored completely safely in Switzerland.