Lately, I’ve realized while trading stocks that just having a good rate of return isn’t enough. The commissions take a much bigger bite out of your profits than you’d expect. Especially if you trade frequently, the impact of fees is really serious. At first, I didn’t really understand what it meant when the fee was 0.1% or 0.2%, but when I ran the numbers, it was genuinely frightening.

I compared brokerage commissions properly, and the differences are bigger than I thought. Even with only domestic stocks, the fees differ from one brokerage to another, and even within the same brokerage, they change depending on the trade amount or the platform. For example, Mirae Asset Securities is about 0.136% on an online basis, Korea Investment & Securities is 0.147%, and Kiwoom Securities can drop to as low as 0.015% on certain platforms. In particular, people who trade small amounts frequently end up losing more because of fixed commissions. At places like Samsung Securities or Shinhan Investment Securities, for trades under 10 million won, they charge an additional 1,500 won or 2,000 won on top of the standard commission—so if you trade often, that adds up to something huge.

The same is true for overseas stocks. For U.S. stocks, most brokerages charge around 0.25%, and then currency exchange fees are added on top. Brokerage exchange rates are often worse than banks, so the actual loss ends up being even larger. That’s why, when investing in foreign currency, it’s better to exchange in advance when the exchange rate is favorable.

When comparing brokerage commissions, what matters is first identifying your own trading style. Because the fee criteria you should look at are different for someone who frequently does small day trades versus someone who makes one or two trades with large amounts. A place with no fixed fees might be better, or a place where the fee gets lower as your trade amount increases might be better.

Also, most brokerages run commission waiver events targeting new or dormant customers. Mirae offers up to 90 days, and Shinhan Investment waives U.S. stock commissions for up to 1 year. If you make proper use of these benefits, you can significantly reduce your initial trading costs. However, the key is to check the benefit conditions in advance and apply during the period when you’ll trade the most actively.

You also can’t ignore the power of compounding. If you trade 10 times with 1 million won each time, assuming you earn 10% per trade, then the final profit differs by hundreds of thousands of won between a 0.1% commission and a 0.2% commission. The larger the trade amounts and the higher the frequency, the more that gap grows.

In the end, the most important way to reduce commissions is choosing a brokerage that fits your trading pattern. Different brokerages are advantageous for different people—those who trade frequently with small amounts, those who trade large amounts at once, and those who focus on overseas stocks. Carefully comparing brokerage commission structures and finding the most favorable option for you is ultimately the first step to improving your rate of return. Commissions are an unavoidable cost, but if you manage them wisely, you can reduce them enough.