You have a one-day risk number. What happens if you plan to hold a position for ten days, or a month, or a year? And how do you handle the fact that selling a large block of bonds is nothing like selling a few shares of a big, familiar stock? This chapter answers both questions. We start with the simple scaling rule many people learn first, then uncover its hidden traps, and finally build a more honest picture of risk that includes the cost and time needed to exit a position in the real world.