Critical consequences flow from accepting or rejecting the view that forward rates predict future yield curve shapes and currency exchange rates. A persistence factor reflects the expectation that interest rates will persist at their current levels rather than evolving into their forward rates. A persistence assumption of 1 anticipates that spot rates will persist, and a persistence assumption of zero anticipates that they will give way to forward rates. A global investor with a persistence assumption of zero for all rates faces uniformly flat expected return curves and has no incentive to seek higher returns by accepting duration or currency risk. An investor with a persistence factor of 1 anticipates rewards for accepting risks by extending duration along positive yield curves or making unhedged investments in higher yielding currencies, for example. Investors often depend on implicit expectations of this type; the persistence model can make such expectations explicit and aid in evaluating their credibility and consequences.