Hi fus1196
Yes, it does.
Switzerland has a so-called integrated ticketing system. It means, regardless of the operator, you can buy the tickets with any public transport company, the price will always be the same - there is no competition. The Golden Pass Panoramic Express, however, is actually jointly operated by MOB, BLS, and Zentralbahn, the latter being a subsidiary of SBB.
Best regards,
Roland