A method and apparatus relate to recognizing anchored patterns from an input stream. Patterns from a plurality of given patterns are marked as anchored patterns. An anchored state tree for the anchored patterns of the plurality of given patterns is built, including nodes representing a state of the anchored state tree. For each node of the anchored state tree, a failure value equivalent to a node representing a state in an unanchored state tree representing unanchored patterns of the plurality of given patterns is determined.