The assets-under-management model for financial planning firms has become increasingly popular in recent years. However, its rising popularity has also brought a great deal of criticism, especially regarding the volatility of revenues as markets cycle up and down. As a result, some firms have begun to shift to a retainer-style model in an attempt to smooth out fees, rather than pricing on a strictly AUM basis.
Unfortunately, though, an annual retainer model where clients have to write a check for services makes the fee significantly more "salient" and can actually force firms to either cut prices or work harder to generate the same income, and may result in worse client attrition during down markets as fee-sensitive clients choose not to renew during difficult times.
As a result, some firms that shift to annual retainers are even shifting away from retainers and back to AUM pricing after a few years of business pain! Of course, the reality is that the AUM model can't serve all clients, and retainers may be necessary in some segments of the marketplace; nonetheless, in situations where there is a choice, the AUM model may have far more longevity than some expect.