A search is now underway for a new CEO of CareGroup after James L. Reinertsen resigned last month as the chief executive of both CareGroup—a Harvard affiliated umbrella organization of six Massachusetts hospitals—and its flagship, the Beth Israel Deaconess Medical Center (BIDMC).

Since its creation during a wave of hospital mergers, CareGroup has struggled financially.

CareGroup’s future health is of crucial importance to Harvard, say University and Medical School officials.

Unlike many medical schools, Harvard doesn’t own the hospitals where its students are trained. But since twenty percent of HMS students are trained at BIDMC, officials say that the continuing financial viability of CareGroup is a concern.

In announcing Reinertsen’s resignation last month, CareGroup Chairman John P. Hamill thanked Reinertsen for his efforts but said that the hospitals’ fortunes had not improved quickly enough.

“[W]hile the results for this year will be better than last year, they will not meet expectations. The boards of both CareGroup and BIDMC have agreed that the scope of the turnaround effort…needs to be enhanced,” Hamill wrote in a statement.

CareGroup continued to hemmorage financially under Reinertsen’s direction, albeit at a slower rate.

Hamill will be leading efforts to find Reinertsen’s successor.