CITY OF COMMERCE, Calif. — Andy Giancamilli, a former chief executive officer of Katz Group Canada Ltd. and past chairman of the National Association of Chain Drug Stores, has been named interim president and CEO of 99 Cents Only Stores.

The extreme value store chain said late Tuesday that Giancamilli, its chairman, takes over from Stéphane Gonthier, who has resigned.

Giancamilli, who has served as a board member of 99 Cents Only since 2012, was named as chairman on April 20. The chain said Giancamilli’s appointment as chairman was made to help guide the company through its next phase of growth and was based on his broad experience in leading several retail businesses.

“In my role on the board over the past three years and more recently as chairman, I have gained a deep understanding of the drivers of the 99 Cents Only business and its distinctive and passionate corporate culture,” Giancamilli said in a statement. “I look forward to working with the members of the senior management team and the board to ensure a smooth transition. Our plan during this time is to continue business as usual while we work to execute on the company’s growth strategies as one of the leading extreme-value retailers in the country.”

Overall, 99 Cents Only operates 384 stores in California, Texas, Arizona and Nevada. The stores offer a wide assortment of name-brand and other competitively priced merchandise and seasonal product offerings.

The company noted that Giancamilli has more than 30 years of experience in leading large retailers. He served for more than eight years as president and CEO of Katz Group Canada, which during his tenure had over 1,800 drug stores in Canada, including Rexall. Before that, he was with Canadian Tire Corp., a Canadian retail conglomerate, and was president and chief operating officer of Kmart Corp. He has also held senior leadership positions at Perry Drug Stores, Inc., a U.S.-based drug store chain, where he began his career in 1975.

“We would like to thank Stéphane for his service. He has been instrumental in leading 99 Cents Only Stores through a transformative period of dynamic change,” stated David Kaplan, a 99 Cents ONly board member and senior partner of Ares Management. “The board of directors is looking forward to having Andy on the team with our dedicated ‘99ers’ as we continue to expand our unique brand of extreme value.”