As I always say unit trusts is like "heads you lose, tails i win" kind of scenario. Even if you're losing or winning the fund managers gets a share of your money from the management fees with NO liabilities.

The money comes from you if you make profit, they also make a profit out of the fees. If you lost 15% they will also make a profit
from the fees.
Either way, the unit trust holders hold all the risk, not the fund managers.