Techniques are disclosed for tracing a ray within a parallel processing unit. A first thread receives a ray or a ray segment for tracing and identifies a first node within an acceleration structure associated with the ray, where the first node is associated with a volume of space traversed by the ray. The thread identifies the child nodes of the first node, where each child node is associated with a different sub-volume of space, and each sub-volume is associated with a corresponding ray segment. The thread determines that two or more nodes are associated with sub-volumes of space that intersect the ray segment. The thread selects one of these nodes for processing by the first thread and another for processing by a second thread. One advantage of the disclosed technique is that the threads in a thread group perform ray tracing more efficiently in that idle time is reduced.