Less than a week after vowing to make changes to improve its brands, Gap ( GPS) announced that two top executives from its struggling Gap and Old Navy chains will leave the company. Denise Johnston, president of Gap Adult, is leaving the company effective Friday. Gap Brand North America President Cynthia Harriss will oversee the adult business until a successor is named. Meanwhile, the company named Karyn Hillman senior vice president of merchandising for the Gap Adult division. Hillman previously worked in merchandising for the company's Banana Republic division -- the retailer's only chain that has been doing well in recent months. At Old Navy, Ivy Ross, the executive vice president of product design, will leave effective Jan. 17. The company is searching for a replacement. In the meantime, the design team will report to recently installed Old Navy President Dawn Robinson. On Thursday, Gap reported disappointing holiday sales and slashed its earnings projections. At the Gap chain, same-store sales sank 9% in December, while Old Navy same-store sales tumbled 10%. At the time, the company said it is reviewing brand strategies for Gap and Old Navy and that it is "committed to making the necessary changes to improve performance." This week, Gap shares have surged amid reports that the company has hired Goldman Sachs to explore strategic alternatives, including a potential company sale. Gap has declined to comment on the reports, calling them rumor and speculation. Shares of Gap recently were down 35 cents, or 1.7%, to $19.84.