The story
SBB GmbH was formed in 2005 from the merger of two companies: a different SBB GmbH, and EuroTHURBO. Swiss Federal Railways founded the original SBB GmbH in 2002 to operate the S5 and S6 services of the Basel S-Bahn. That company was based in Lörrach, near Basel. THURBO, itself a subsidiary of Swiss Federal Railways with support from the canton of Thurgau, founded EuroTHURBO in 2003 to handle THURBO's cross-border operations on the Seehas route, which belongs to Bodensee S-Bahn (Lake Constance S-Bahn).
In addition to the Seehas and Basel S-Bahn services, the company began operating the Schaffhausen S-Bahn service between Erzingen and Schaffhausen in 2018, and between Singen (Hohentwiel) and Schaffhausen in 2022.
From Wikipedia’s article on SBB GmbH, shared under CC BY-SA 4.0.5