Popular investment advice recommends that stock/bond and stock/wealth ratios should rise with investor risk tolerance and investment horizon respectively, prescriptions that are difficult to reconcile with the simple mean-variance model. We show that extending the mean-variance model to include...

Racehorse trainers operate unregulated asset management businesses in which the assets owned by outside clients compete with those owned by trainers for the latter’s time, care, and attention. However, market mechanisms appear to deal effectively with the resulting agency problem in situations...