Recently, I've seen many novice investors ask a common question: Will stock prices definitely fall on the ex-dividend date? Is it more cost-effective to buy on the ex-dividend day? Let me share my observations.

Honestly, many people have a misconception about dividend-paying stocks, thinking that stock prices must drop on the ex-dividend date as a rule. But based on my experience and market data, that's actually far from always being the case.

Let's start with the basic logic. When a company announces a dividend, theoretically, the stock price should decrease because the company's assets have reduced. For example, if a company's stock is $35, including $5 of excess cash, and it decides to pay out $4 in cash dividends, then on the ex-dividend date, the theoretical stock price should be $31. This logic makes sense. But the problem is, the market never moves solely according to theory.

I've looked at the historical performance of Coca-Cola and Apple. Interestingly, these high-quality companies often see their stock prices rise on the ex-dividend date. For instance, on November 10, 2023, Apple's stock rose from $182 to $186 on the ex-dividend date, a significant increase. Industry leaders like Walmart and Johnson & Johnson also often experience gains contrary to the typical expectation. The reason is simple: market sentiment, company performance, industry outlook—these factors often have a bigger impact than the ex-dividend effect itself.

Now, returning to whether buying on the ex-dividend date is cost-effective. My view is that it depends on three perspectives.

First, look at the stock price performance before the ex-dividend date. If the stock has already risen to a high level before the ex-dividend date, many investors will take profits early. Entering at this point might face significant selling pressure and may not be the best timing.

Second, consider historical trends. Statistically, stocks tend to continue declining after the ex-dividend date rather than rising, which is unfavorable for short-term traders. However, if the stock price falls to a technical support level and shows signs of stabilization, it could actually be a good buying opportunity.

Third—and I think most importantly—look at the company's fundamentals. If the company has solid fundamentals and is a leader in its industry, the ex-dividend does not damage its intrinsic value. On the contrary, a price pullback can provide an opportunity to buy quality assets at a lower price. For such companies, buying on the ex-dividend date and holding long-term is often more cost-effective than reacting to short-term fluctuations.

Another concept worth noting is the difference between "ex-rights fill" and "discounted rights." Filling rights means the stock price gradually recovers to pre-ex-dividend levels after the ex-dividend date, indicating investor confidence in the company's prospects. Discounted rights, on the other hand, mean the stock remains depressed, often reflecting market concerns about the company's future.

Finally, a reminder about implicit costs. If you buy on the ex-dividend date in a regular taxable account, although the stock price drops, you still have to pay taxes on the received cash dividends—this is a tax trap. Additionally, Taiwan's stock market involves transaction fees and stamp duties: about 0.1425% of the transaction amount (adjusted by the discount rate) for buying and 0.3% (ordinary stocks) or 0.1% (ETFs) for selling. These are real costs that impact your returns.

In summary, buying on the ex-dividend date isn't necessarily advantageous or disadvantageous—it depends on the company's quality, market environment, and your investment goals. The logic for short-term trading versus long-term value investing is completely different. If you're after dividend income, focus on whether the company is worth holding long-term, rather than obsessing over the small price fluctuations on the ex-dividend date.