Anti-trust (at least to me) has a connotation with trust-busting and splitting up companies, but I'd be interested in the ramifications of restricting Ticketmaster to creating contracts no longer than, say, 6 months.

On one hand, free markets involve sellers and buyers coming together freely which exclusivity contracts prohibit, but on the other hand exclusivity contracts are nominally voluntary agreements which is a free exchange. Perhaps free-exchange simply isn't a useful framing here.