Tontines (the products) do not require guarantees because by design they are ALWAYS fully funded.

Tontine Trust Limited (the company) will be a fully regulated entity shortly after completion of the TON Token Sale.

The market price of TON Tokens available for purchase are not guaranteed to stay at the same price as the price at which they will be sold. In fact I would be very surprised if they if they did stay at the same price.