The “at risk” part of “Construction Manager at Risk” means that the CM is contractually responsible for the construction (but not the design) of the project. If there is a construction defect, if the work falls behind schedule, if there are unapproved cost overruns, the CM at Risk is liable for them. The owner does not need to determine which subcontractor (or combination of subcontractors) caused a particular problem because the CM has to make it right regardless. 

In contrast to the Design/Bid/Build model, the CM is typically involved in the pre-construction phase of the project, offering cost-estimating, scheduling, and other services to the owner and providing feedback to the architect during design development.

Under this model, the CM is not responsible for design, but rather the architect who also serves as an owner agent.