They actually do quite well but not because they are trying to invest in specific holdings they have information on. (thecollegeinvestor.com)
Concededly, the Judicial Branch website does provide prompt access to the original «slip opinions,» but these lack the editorial revisions that occur later during the publication process and also, of at least equal importance, they lack the volume and page numbers by which specific holdings of those cases must be cited in any subsequent legal proceeding. (citeblog.access-to-law.com)
Related parties have certain specific holding periods. (havenexchange.com)