While trading stocks, I often only worry about my return rate, but I’ve found that fees can cause me to lose money. Recently, I realized that this actually has a bigger impact on my final profit than I expected.

When trading domestic stocks, fees paid to the brokerage firm—such as brokerage commission for order execution—are included, along with exchange and Korea Securities Depository and its affiliated fees, etc. For overseas stocks, on top of this, currency exchange fees are added. For U.S. stocks, for example, it’s usually enough to assume around 0.25%. However, when you compare domestic stock trading fees, you can see that the differences among securities firms are substantial.

Looking at the status of major securities firms: Mirae Asset Management charges 0.136% domestically; Korea Investment & Securities and Samsung are around the 0.147% range; and Kiwoom, based on the HeroMUN4 standard, is much cheaper at 0.015%. Shinhan Investment charges 0.139% plus a fixed fee of 2,000 won for transactions under 30 million won. The point to note here is the fixed fee—if you do frequent small short-term trades, it can become a surprisingly large burden. If you make 100 trades, the fixed fee alone amounts to 150,000 won.

It’s also important that fees compound over time. If you trade 10 times with 1,000,000 won each time and earn a 10% profit every time, then with a 0.1% fee the final profit is 2.57 million won, while with a 0.2% fee it’s 2.54 million won—so the difference is 30,000 won. The larger your investment and the more frequent your trading, the bigger this difference becomes.

So there are tips you should check when comparing securities firm fees. First, compare fees based on the platform you mainly trade on. Even with the same securities firm, fees can differ depending on whether you trade online, through a mobile app, or with a specific trading tool. Second, make sure to look at new-customer events. Most securities firms offer fee waiver benefits for new or dormant customers for anywhere from 3 months to 1 year. For example, Shinhan Investment does not charge U.S. stock trading fees for up to 1 year.

You also need to pay attention to the trade amount and frequency. If you trade small amounts often, a firm with no fixed fee is better; and if you trade a large amount at once, you should take advantage of the structure where the fee is lower as the transaction amount increases. If you don’t have a plan to buy in installments, trading all at once is one way to reduce fees.

When trading overseas stocks, currency exchange fees are also important. Securities firms often have worse exchange rates than banks, so it’s a good idea to exchange currency in advance when the exchange rate is low, or to check whether the securities firm offers preferential exchange-rate benefits.

In the end, comparing securities firm fees should be tailored to your trading patterns. If you mainly do small short-term trades, you can choose a low-fee firm like Kiwoom; if you’re investing long-term, choosing a firm with good new-customer events is beneficial. The wise approach is to remember that even small fee differences can add up and significantly affect your final profit, and trade accordingly.