HWM affects the incentive fees. It’s a NAV that the manager must exceed before receiving the performance-based incentive fee. A provision to protect clients’ benefits.
It’s usually a nav = the highest year-end value till now if no in/out cash flows, but it may differ due to different fiscal year or agreement on incentive fee. So it could be complex in practice.
It remind me of fee cap, performance netting risk, and max drawdown. But these are more like distractors.