March 13 (Reuters) - Alexion Pharmaceuticals Inc said on Monday it has initiated a company-wide restructuring that will affect about 7 percent of its workforce.

The rare-disease drug maker, which has been looking to steady the ship following the exit of its top management, had 3,121 employees as of Dec. 31.

Alexion's chief executive and chief financial officer resigned in December after the board had lost confidence in them.

"We are investing our resources in key growth drivers, including our portfolio of marketed products," the company said in an emailed statement.

The U.S. biotech's flagship drug, Soliris, has fueled much of the company's growth, but slowing sales in recent quarters and looming competition have made investors jittery.

(Reporting by Ankur Banerjee in Bengaluru; Editing by Shounak Dasgupta)