The Chargeback Rate That Hides in Aggregation

BIN 411111 has a 25% chargeback rate — 125 of 500 transactions — completely diluted into the merchant's overall 3.09% chargeback rate by volume from 19 other BINs. BIN 533221 also runs elevated at 8%, but that's a documented high-risk international BIN category that has always disputed more, not new fraud. Grouping by BIN instead of the merchant total is what surfaces the real breach.