Percentile band (p10 / p50 / p90)

In the Monte Carlo fan chart, p10 means 10% of simulated paths ended below this value, a pessimistic case; p50 is the median path; and p90 means only 10% of paths ended above it, an optimistic case. The gap between p10 and p90 is a direct visualization of how much uncertainty the projection carries — a wide band means the range of plausible outcomes is large, not that any one path within it is more likely than another.