Department stores are maximizing opening hours, closing just one day for Chuseok or Korean Thanksgiving last month for the first time in a decade. Until last year, they took two days off for the holiday.

Shinsegae Department Store started the competition. Rivals Lotte and Hyundai were initially scheduled to close all of their branches on Monday, for the traditional holiday every third Monday of the month, but Shinsegae announced on Nov. 9 it would skip the tradition and open all of its eight branches. It was a shock for the industry, which by gentlemen's agreement took the same day off.

The day after the announcement, Lotte said it was following suit for eight branches in the vicinity of Shinsegae stores. Hyundai cancelled the off-day for all of its 11 branches. The three have decided to open every day next month as well.

The driving force is fierce competition for a larger market share. More business days translate into increased sales for department stores. It is a zero-sum game. Another reason is that the cold winter weather drives people from the streets into department stores.

Shinsegae has come in for some harsh criticism. Critics say behind the decision are disappointing results from its two new branches at Centumcity and Yeongdeungpo. But Shinsegae denies this, claiming both branches exceeded sales targets and staff have been consulted.

"Amid sluggish sales in superstores, only department stores are enjoying booming business. Given this, retailers are competing to rake in as much money as they can while it is still possible," said Prof. Lee Chung-hee of Industrial Economics at Chung-Ang University. But he warned the department stores ought to consider the negative effects