OPERATIONS / SUPPLY CHAIN

New York — American Express has launched a new venture with Twitter, that could lead to a whole new category of shopping.

Foothill Ranch, Calif. — The Wet Seal announced that Barbara Cook, SVP store operations, has resigned from the company to accept a new professional opportunity. Cook will remain with the company until Feb. 20 to assist with transition of her responsibilities.

John Goodman, CEO of The Wet Seal, Inc., commented: “We thank Barbara for her service to the company since joining us in late 2011 and wish her all the best in her new role.”

Salt Lake City -- Overstock.com said Tuesday that chairman and CEO Patrick Byrne will take a leave of absence for medical reasons. Company president Jonathan Johnson will assume Byrne’s CEO duties during the leave, although Byrne will remain chairman of the board.

Byrne, in recent years, had undergone various procedures regarding cardiac issues that may stem from his earlier episodes of cancer, and his leave of absence is associated with these cardiac issues.

Purchase, N.Y. — MasterCard Advisors, a division of MasterCard, and analytics firm Mu Sigma announced a new partnership to develop analytic products toward solving business challenges such as acquiring customers and increasing customer loyalty.

As part of the partnership, MasterCard has acquired an equity stake in Mu Sigma. Additional terms of the deal were not disclosed.

Omaha, Neb. -- Apparel and home décor chain Gordmans announced Monday it has appointed Michael Morand as EVP and chief merchandising officer.

Morand has served as Gordmans' EVP planning, allocation and analysis since 2008. In his new position, he will lead the combined merchandising and planning team and drive the retailer’s continued expansion in both new and existing markets.

Woonsocket, R.I. -- CVS Caremark said Monday it has named Brian Tilzer as SVP, chief digital officer for the drugstore chain.

Tilzer, previously SVP global e-commerce for Staples, is charged with developing and leading CVS digital innovation efforts and connecting current and future digital initiatives.

Sherman Oaks, Calif. — American apparel brand Cherokee Inc. said Monday it has partnered with Chinese hypermarket chain RT Mart to launch an online Cherokee store on China’s largest e-commerce website, Tmall.com.

Cherokee will join Gap, Uniqlo, Adidas and Levi’s, who have each opened retail storefronts on Tmall.com.

Fort Worth, Texas -- In an unexpected move, RadioShack said late Thursday that Walgreen Co. divisional president Joseph Magnacca will take the helm of the beleaguered consumer electronics chain as its new CEO.