Most accountable care organizations (ACOs) participating in the Medicare Shared Savings Program (MSSP) say they are not ready for the upcoming requirement that they accept two-sided risk models. In responses to a survey, 47% of single ACOs and 32% of multi-ACOs said they would leave the Medicare ACO program if required to accept downside risk of loss. About 84% of ACOs said they would need up to six years to prepare for accepting downside risk sharing. About 7.6% said they would never be ready to accept downside risk. About 2.8% said they were already participating in . . .