The company’s stock has declined over its financial performance and the sudden replacement of its CEO.

UnitedHealth Group announced a dramatic leadership shakeup, with former CEO and current chairman Stephen Hemsley stepping back into the top job following the abrupt resignation of Andrew Witty. The move comes at a time of escalating crises for the healthcare giant — including the recent fatal shooting of Brian Thompson,

The executive earlier caused public outrage when he defended the insurance giant’s practice of denying health care claims.

UnitedHealth Group, Inc. UNH has fallen nearly 50% over the past month, fueled by a series of negative catalysts. Several analysts have slashed price targets on the stock, but one analyst has seen enough and downgraded UnitedHealth on Wednesday.

UnitedHealth Group Chairman Stephen Hemsley is returning to helm the health care conglomerate once again. He will replace Andrew Witty effective immediately.

A group of investors this week filed a proposed class-action lawsuit against UnitedHealth Group, alleging that the company withheld information following the murder of UnitedHealthcare CEO Brian Thompson last December.