Korea's top 10 didn't change in a week. Its bottom half turned over 1 in 5.

Korea's best-seller chart reshuffles more than it turns over, and the turnover it does have lands almost entirely in the tail. Over the one clean seven-day span in our archive — July 19 to July 26 — all 10 of Olive Young Korea's top 10 held their place and 87 of the 100 products carried over, but retention falls steadily down the ranking: from 100% at the top to 80% in the bottom half. The head is durable; the tail is where new products break in.

How much of the chart is new each week?

About one in eight. 13 of the 100 products on this week's chart were not there the week before, and 13 dropped out to make room — a 13% turnover across seven days. That is real movement, but it is modest for a best-seller board: the large majority of what tops Korea's shelf one week is still there the next. The chart's week-to-week story is less about wholesale change than about the same cast trading places.

Where does the turnover actually happen?

At the bottom. Retention tracks rank almost perfectly: the top 10 held 100%, ranks 11–25 held 93%, ranks 26–50 held 92%, and ranks 51–100 held 80% — meaning 10 of the 50 products in the bottom half were new. So a brand fighting for a debut is really fighting for a spot in the lower half of the chart; the upper half is close to a standing order. The new entrants this week fit that pattern — an Anua dark-spot serum, a TOCOBO sun stick, a numbuzin mask pack — products that broke in, but broke in below the established leaders.

Does anything move at the very top?

Ranks move; occupants don't. Within the top 10 the order shifts week to week — products rise and fall a few places — but the ten names stay the same, and MEDIHEAL's Essential Mask set has held the #1 slot across every week in our archive so far. That is the pattern the whole chart rhymes with: motion without much replacement. Positions are contested constantly; membership, especially near the top, is not.

What this does and doesn't tell you.

It rests on a single week, and we say so plainly. Our archive is only three weeks deep, and this week's snapshot (captured July 26) sits just a day before a same-week re-capture, so the one clean seven-day transition we can measure is July 19 to July 26 — that is the window this piece uses, matched by product ID on Olive Young Korea's public top 100. One transition is a reading, not a trend: the 13% weekly turnover and the top-to-bottom retention gradient are what a week showed, not a law, and we will know whether they hold as the archive deepens. What is already clear is the shape — a chart that moves at the margins and holds at the core — and it is the kind of claim our weekly snapshots are built to keep testing.