Majors? Do I have a better chance with one?

I’m thinking about going into fields regarding math/econ/finance/stats. I don’t really know which one I should major in so should I apply undecided in the sciences school or apply to one of these majors? Is there a disadvantage on the admissions standpoint if I apply undecided?

UCLA’s College of Letters and Sciences does not admit by major so it will make no difference. BTW, UCLA does not have a Finance major.