£2 billion has been spent on 12 hospital mergers over the past five years despite growing evidence that NHS mergers do not resolve the difficulties they are intended to address, according to a new report from The King’s Fund. The report reviewed 20 mergers of NHS trusts and foundation trusts between 2010 and 2015. The vast majority of these mergers were initiated by national regulators or special administrators, with the aim of helping NHS trusts to become foundation trusts or rescuing them from financial difficulty. Our analysis found that: in many cases, there was no clear rationale for merger, with serious weaknesses in the assessment of alternative options and the articulation of the case for merger mergers are pursued despite growing evidence that they do not deliver the intended benefits, with little recognition of the disadvantages of creating larger, more complex organisations and despite evidence that they often act as a barrier to delivering service changes the merger process is complex, time-consuming and costly, with as many as 10 separate bodies involved and some organisations taking four or five years to complete the process. The report found that the bulk of allocated funding was spent on writing down historic debts, covering deficits and capital investment, rather than on delivering the service changes needed to make the merged organisations sustainable. This suggests that mergers are unlikely to address the causes of the organisations’ difficulties and are pursued as a way of secure financing that would otherwise not be available. While the report foresees a continuing role for mergers in the NHS, it calls on NHS leaders to rule out mergers as a route for NHS trusts to gain foundation trust status or as a response to financial failure. Instead, alternative strategies should be developed that address the underlying problems faced by struggling hospital trusts, based on organisations working together in local systems of care.