One brand holds 8 of Korea's 100 best-sellers. Most brands hold one.

Korea's best-seller chart is concentrated at the top and thin everywhere else. In Olive Young Korea's top 100 for 2026-W31, the ten largest brands hold 39 of the 100 slots, and a single brand — MEDIHEAL — holds 8 of them, including the #1 product of the week. Below that crowd, the chart empties out fast: of the 60 brands that place at all, 39 appear exactly once.

How concentrated is the top of the chart?

The top is dominated by a handful of names. MEDIHEAL holds 8 of the 100 slots (ranks 1, 4, 6, 18, 19, 20, 48 and 82), Torriden holds 7, CLIO holds 5 and Abib holds 4. The three biggest brands together account for 20 of the 100 slots; the top five account for 27; the top ten account for 39. That means fewer than a fifth of the charting brands hold roughly two-fifths of the chart — on a single retailer, Olive Young Korea, in a single week.

Is it 100 products, or a few franchises in many forms?

It is closer to a few franchises. The concentration at the top is driven less by ten separate hit products than by a small number of hero lines sold in many forms. Torriden's 7 slots are almost entirely one product — its Dive In low-molecular hyaluronic-acid line — charting as different sizes and variants. MEDIHEAL's 8 slots cluster into two franchises: sheet-mask packs (ranks 1, 4 and 20) and toner pads (ranks 6, 18 and 19), plus a gel mask and one serum. Sets, double-packs and multi-type bundles are a large part of what keeps these brands on the board, which is why "100 products" overstates how many distinct formulas Korea's top 100 actually represents.

What does the long tail look like?

The long tail is most of the brand list. Of the 60 distinct brands on the chart, 39 — 65% — hold a single slot: beplain's mung-bean cleanser at #2, UNOVE's hair mask at #3, d'Alba's tone-up sun cream at #5, BIODANCE's collagen mask at #7, and dozens more that each land one product and no other. So the same chart that looks top-heavy from the #1 spot looks wide open from the bottom: getting one product onto Korea's best-seller list is common; getting a second one on at the same time is not.

What this does and doesn't tell you.

It tells you about chart position, not sales volume. These are ranks on Olive Young Korea's public best-seller list for 2026-W31 — the country's largest health-and-beauty retailer — not units sold, and one retailer is not the whole Korean market. Two caveats cut against reading this as pure brand strength: sets and variants of one product each occupy their own slot, so a brand that sells its hero item in five pack sizes can look like five entries; and a top-100 cut-off hides how close the #61 brand is to the #59 brand. What survives those caveats is the shape: a short, variant-heavy head and a long single-slot tail, stable enough to measure the same way every week. That shape is the thing we will track — whether the head concentrates further, and which single-slot brands come back with a second product.