Determining whether it is better to purchase shares or units before or after a dividend ex-date depends on an investor's overall strategy, as neither timing guarantees an immediate financial advantage. When a security goes ex-dividend, its market price typically drops by an amount roughly equal to the payout value. Buying before captures the upcoming distribution payment but incurs immediate tax liabilities on that payout, whereas buying after allows an investor to acquire the asset at a lower ex-dividend price without the immediate tax event, making total return and personal cash flow goals the primary deciding factors.