I never saw any deed or similar, just a confidential report that noted the contributions the local Canton had made to the business. It could be that legal title to the land would revert back to the Canton if the company withdrew, so that a ground rent would become payable (or an option to buy the land might be offered) should anyone buy the buildings that the company had built. Even so, given the cost of buying land in Switzerland (and this was a large, prime location site in the middle of an important town) being given land free of rent or purchase costs is a huge incentive.
I always wondered if the local tax payers knew of these sort of arrangements as, despite perceptions, the Swiss do end up paying quite a lot of taxes, with everyone from the Canton to the local churches all taking a cut. Perhaps more significantly the Swiss seem to get little back in return, with Switzerland not even having a European-style health service. In Switzerland all health cover is paid for via expensive private insurance policies, which for many people only really cover serious illnesses requiring hospitalisation, with anything costing (typically) less than 2000 Swiss francs being paid for in full by the patient. Many Swiss travel to France to get medical care, especially dentistry, lab tests and so forth.
Perhaps even more than the US, Switzerland seems to be focused on doing whatever serves the needs of 'business', rather than the people who live there.