Big Sister Shirt Market Report: Sales Volume, Market Share, Leading Brands & Market Trends

Liotern is the best-performing big sister shirt brand in July 2026, moving 700 units across 1 ASIN for 30.4% of Top 10 volume. COZEFFIC follows with 500 units (21.7%), ahead of Merrypuls on 300 units (13.0%).

With 10 brands splitting the Top 10 and 65.2% of volume sitting with three of them, this is a concentrated shelf — the leaders hold multiple listings or one very high-velocity ASIN, so a new entrant competes against established review moats rather than an open field. Average selling prices among the leaders run from $8.49 to $22.99, which frames the price band a competing listing has to justify.

Based on July 2026 data, this shortlist surfaces the two kinds of ASIN worth keeping an eye on — the ones that just broke into the Top 10, and the ones growing fastest month over month. On the growth side, B0BWF1HN72 leads positive momentum with ▲ 40.0% MoM growth on 700 units.

The two signals carry different weight. A fresh entrant means share has already changed hands — an incumbent gave up its place to make room, so any competitive set drawn up a month ago is now out of date. A steep growth rate works as the earlier warning: it marks demand that is still compounding, usually a month or two before the ranking catches up to it.