A type of conditional probability fetcher prefetches data, such as for a cache, from another memory by maintaining information relating to memory elements in a group of memory elements fetched from the second memory. The information may be an aggregate number of memory elements that have been fetched for different memory segments in the group. The information is maintained responsive to fetching one or more memory elements from a segment of memory elements in the group of memory elements. Prefetching one or more remaining memory elements in a particular segment of memory elements from the second memory into the first memory occurs when the information relating to the memory elements in the group of memory elements indicates that a prefetching condition has been satisfied.