An odd headline from the Sunday Times (15 March 2009).
The noun phrase is Swiss’ tax haven reputation, with the head noun reputation. The use of the possessive, Swiss’, is plain wrong — for the same reason, we do not say things like *the French’s reputation for being resistant to speaking English. Rather, we need to rephrase this with a preposition phrase: the reputation of the Swiss/French.
But since Swiss is an adjective, all the headline writer needed to do was omit the apostrophe: Swiss tax haven reputation at stake.