If you start with high risk capacity, then after a fall in the markets your capacity gets even higher. If you start with low capacity, then lower market values means an even lower capacity. If those changes are large enough, then the risk profile could change enough to justify a portfolio change.If you’re taking withdrawals but happen to have a high risk capacity, you needn’t worry: market falls become an opportunity to increase risk, not something to protect against.Whether the investor is in the position of a market fall being a threat, an opportunity, or a matter of total indifference, the answer to what to do should be systematic: clear, concise, and calculated; it is driven by risk capacity.