Recently, many people have been asking a question: Will stock prices definitely fall on the ex-dividend date? Should I buy before the ex-dividend date, or is it more cost-effective to buy after?

Honestly, this is a very good question because many novice investors are indeed troubled by it. High-dividend stocks have become increasingly popular in recent years, even Warren Buffett has allocated more than half of his assets to such stocks, but many still have only a superficial understanding of the ex-dividend mechanism.

First, let’s state the conclusion: stock prices do not necessarily fall on the ex-dividend date, and this is a common misconception.

Theoretically, it makes sense that stock prices would adjust downward on the ex-dividend date. When a company distributes cash dividends, it means the assets decrease, so the stock price should adjust accordingly. For example, suppose a company’s stock price is $35, which includes $5 in cash reserves per share. If the company decides to pay out $4 per share in dividends, leaving only $1 in reserve, then theoretically, on the ex-dividend date, the stock price should adjust from $35 to $31. This is a mathematical inevitability.

But in reality, things are much more complicated than the theory suggests. Looking at historical data, stock prices on the ex-dividend date can go up or down. Take Coca-Cola as an example: most ex-dividend dates see a slight decline, but on September 14, 2023, and November 30, 2023, the stock actually rose slightly. Apple is even more extreme: on November 10, 2023, the stock price rose from $182 to $186 on the ex-dividend date, an increase of nearly 2.2%. Leading stocks like Walmart, Pepsi, and Johnson & Johnson also often see stock price increases on ex-dividend days.

Why does this happen? Because the movement of stock prices on the ex-dividend date is influenced by multiple factors, not just the dividend distribution. Market sentiment, company performance, and the overall market environment all play roles. Tech stocks have been in favor lately, so Apple can still rise on the ex-dividend date. This explains why, even with the same ex-dividend event, different stocks and different periods can show completely different performances.

So, is it worthwhile to buy stocks after the ex-dividend date? That depends on several perspectives.

First, you need to understand two concepts: “dividend recovery” and “dividend sticking.” Dividend recovery means that after the stock goes ex-dividend, its price drops but then gradually recovers or even returns to pre-dividend levels, indicating investors are optimistic about the company's prospects. Dividend sticking means the stock price remains low and does not recover, often reflecting investor concerns about the company's future.

If the stock price has already risen to a high level before the ex-dividend date, many investors choose to realize profits early, especially those looking to avoid taxes. Entering at this point carries risks because the stock price may already include excessive expectations and could face selling pressure.

Historical data shows that stocks tend to decline rather than rise after the ex-dividend date, which is not friendly for short-term traders. However, if the stock price falls to a technical support level and begins to stabilize, it could be a good buying opportunity.

The truly cost-effective approach is to consider the company's fundamentals. If the company has solid performance and industry-leading position, the price drop on the ex-dividend date is just a normal adjustment, not a reduction in value. In such cases, buying after the ex-dividend date and holding long-term is often more profitable because you’re purchasing high-quality assets at a lower price.

Another hidden cost to be aware of: if you buy ex-dividend stocks in a regular taxable account, you will face unrealized capital losses on the ex-dividend date, and you also need to pay taxes on the dividends received. This can be costly for short-term investors. In Taiwan’s stock market, transaction fees are calculated as stock price times 0.1425% times a discount rate (usually 50-60%), plus a 0.3% transaction tax when selling stocks, and 0.1% for ETFs. These costs can significantly compress short-term profit margins.

Some investors consider using contracts for difference (CFDs) to capitalize on short-term fluctuations before and after the ex-dividend date. This method doesn’t require actual stock ownership, so no dividend tax is paid, and leverage can be flexibly adjusted, allowing small margin control of large positions. If the stock price moves as expected, short-term returns can far exceed those from direct stock holding and dividend collection. However, this approach carries higher risks and should be used cautiously according to your risk tolerance.

In summary, the movement of stock prices on the ex-dividend date results from multiple factors. The key is to make decisions based on your investment goals and risk appetite. Long-term investors with solid fundamentals should consider buying after the ex-dividend date and holding, which can yield stable returns. Short-term traders need to carefully evaluate costs and risks before acting.