Korean stocks are top-heavy — and the company count hides it
Korea and Japan list almost the same number of companies that file a revenue line. The share held by the ten largest is about twice as high in Korea. Read from filed accounts, not from share prices.
The finding
Korea has 2,487 listed filers with a revenue line; Japan has 2,419. Within four per cent of each other.
But Korea's ten largest take 34.9% of all revenue filed in that market, against Japan's 17.0% — about 2.1 times the share.
Counting companies tells you nothing about how the revenue is spread.Two markets of the same size can be built completely differently.
How much the largest firms take
Each row is one market, counted separately in its own currency. Only shares are compared — never amounts. A share is unit-free; a sum across currencies is not.
| Market | Year | Filers counted | Top 1 | Top 10 | Top 20 | Top 100 |
|---|---|---|---|---|---|---|
| Korea | 2025 | 2,487 | 9.2% | 34.9% | 46.2% | 73.9% |
| Japan | 2026 | 2,419 | 3.8% | 17.0% | 24.6% | 51.9% |
| Taiwan | 2026 | 1,054 | 16.8% | 52.4% | 63.9% | 84.7% |
Fiscal years differ between markets, so each market's own year is printed rather than forcing them onto one line. Firms that filed no revenue line are left out: Korea 222, Japan 247, Taiwan 20. Most are banks and insurers, which report differently. They are not counted as zero.
Korea's ten largest, one by one
Share of all revenue filed by Korean listed companies in 2025. Names are as filed in English.
| # | Company | Share of all filed revenue |
|---|---|---|
| 1 | SAMSUNG ELECTRONICS CO,.LTD | 9.2% |
| 2 | HYUNDAI MOTOR CO | 5.1% |
| 3 | SK Inc. | 3.4% |
| 4 | KIA CORPORATION | 3.1% |
| 5 | KOREA ELECTRIC POWER CORPORATION | 2.7% |
| 6 | SK hynix Inc. | 2.7% |
| 7 | LG ELECTRONICS INC. | 2.5% |
| 8 | SK Innovation Co., Ltd. | 2.2% |
| 9 | HANWHA CORP | 2.1% |
| 10 | HD HYUNDAI CO.,LTD. | 2.0% |
Everything outside the top 100 — 2,387 companies — adds up to 26.1% of the total.
Taiwan is the other extreme
Taiwan counts 1,054 filers — fewer than half of Korea's — and its ten largest take 52.4%, with the single largest alone at 16.8%.
Lined up, the three markets sit in a clear order: Japan 17.0% → Korea 34.9% → Taiwan 52.4%.
What this is and is not
This is filed revenue, not market value. We do not use share prices or market capitalisation anywhere on this page. A price is a bet on what a company will earn; revenue is what it reported earning.
Concentration is not a verdict. A market where a few firms earn most of the revenue is not thereby worse or riskier — it is differently shaped. What it changes is what an index tracks, and that is worth knowing before you read one number as "the market".
We do not say what to do with this. Nothing here is investment advice. The counts, the year and the exclusions are all printed so the figure can be checked rather than taken.