Breach Exposes Tens of Millions of Customer Records On November 29, Coupang disclosed that personal information of 33.7 million customers—including names, phone numbers, email addresses and delivery details—had been compromised, marking the largest breach in the company’s history and affecting the majority of its active user base [1][2][3][4].

Daily Active Users Spike Then Plummet After the announcement, daily active users (DAU) surged to a record 17.98 million on December 4, up from 17.45 million the day before, as shoppers logged in to check accounts and change passwords [3]. Within four days, DAU fell to 17.78 million and then dropped another 1.81 million to 16.17 million by December 8, representing the first post‑breach decline after an initial three‑day rise [2][1].

Competitors Capture Shifting Shoppers The day after the leak, Gmarket’s DAU rose by 250,416 users, while Naver and 11Street recorded modest increases, indicating that some customers migrated to alternative e‑commerce platforms amid concerns over data security [1].

Regulators Probe Account‑Termination Practices The Korea Communications Commission opened an investigation into whether Coupang’s restrictions on account termination violate consumer‑rights laws, adding regulatory pressure to the company’s crisis response [2].

Small Sellers Report Uneven Sales Fallout Numerous small‑business sellers reported double‑digit sales declines, with one owner seeing a 30 % order drop and another losing up to 90 % of revenue after the breach; however, fashion and cosmetics merchants experienced less impact due to longer purchase cycles, highlighting sector‑specific effects while roughly 75 % of Coupang’s merchants remain SMEs [4].