as top researcher michael kitces said :
Cash reserve strategies that hold aside several years of spending to avoid liquidations during bear markets are a popular way to manage withdrawals for retirees. In theory, the strategy is presumed to enhance risk-adjusted returns by allowing retirees to spend down their cash during market declines and then replenish it after the recovery. Yet recent research in the Journal of Financial Planning reveals that the strategy actually results in more harm than good; while in some scenarios the cash reserves effectively allow the retiree to “time” the market by avoiding an untimely liquidation, more often the retiree simply ends out with less money due to the ongoing return drag of a significant portfolio position in cash. As a result, the superior strategy for those who want to alter their asset allocation through market volatility (the effective result of spending down cash in declines and replenishing it later) appears to be simply tactically altering asset allocation directly, without the adverse impact of a cash return drag. Nonetheless, this still fails to account for the psychological benefits the client enjoys by having a clearly identifiable cash reserve to manage spending through volatility – even though the reality is that it results in less retirement income, not more.