Neutral: market shocks are symmetric around zero (up and down are equally likely).
Slightly pessimistic: small bias toward negative years. Positive spikes are a bit less frequent; drawdowns are a bit more common.
Pessimistic: stronger negative skew. Big up years are rarer; negative years occur more often and tend to be deeper.
Implementation detail: the simulator draws a “market shock” each year and applies a mild (slight) or stronger (pessimistic) downward skew to that shock before it is
correlated into each bucket.