Under the March 2011 proposal, ACOs that chose the one-sided model would participate in shared savings for the first two years and assumed shared losses in addition to the shared savings for the third year. In the two-sided model, ACOs shared savings and losses for all three years. Although the ACO assumed less financial risk in the one-sided model, ACOs had a maximum sharing rate of 50% in the one-sided model and a higher maximum sharing rate of 60% in the two-sided model, provided that the minimum shared savings rate threshold of 2% was reached. For both models, the shared loss cap increased each year. However, initial feedback raised concerns regarding ACO's financial risk and possible cost savings. On October 20, 2011, DHHS released the final regulations that altered providers' financial incentives. Under the one-sided model, providers no longer assumed any financial risk throughout the three years and continued to share in cost savings above 2%. Under the two-sided model, providers assumed some financial risk, but share in any savings that occur (no 2% benchmark before provider savings accrue). Value-Based Purchasing (VBP) links provider payments to improved performance by health care providers. This form of payment holds health care providers accountable for both the cost and quality of care they provide. It attempts to reduce inappropriate care and to identify and reward the best-performing providers. VBP Levels 1, 2, & 3 describe the level of risk providers choose to share with the Managed Care Organization. VBP risk levels allow providers to gradually increase the level of risk in their contracts. Levels of risk offer a flexible approach for providers in moving to VBP. Level 1 VBP: FFS with upside-only shared savings available when outcome scores are sufficient. Has only an upside. Receives FFS Payments. Level 2 VBP: FFS with risk sharing (upside available when outcome scores are sufficient). Has upside and downside risk. Receives FFS Payments. Level 3 VBP (feasible after experience with Level 2; requires mature contractors): Prospective capitation PMPM or Bundle (with outcome-based component). Has upside and downside risk. Prospective total budget payments. CMS established five domains in which to evaluate an ACO's performance. The five domains are "patient/caregiver experience, care coordination, patient safety, preventative health, and at-risk population/frail elderly health". ACOs are composed mostly of hospitals, physicians and other healthcare professionals.