In German, unlike in English or Swedish, there are two different perfect auxiliaries: the more frequently used haben and the auxiliary sein. The latter only occurs with a restricted group of verbs. Against the traditional view, it has recently been argued that both periphrases do not form a homogenous category, i. e. there was no grammaticalisation of sein + second participle at all. According to this view the periphrases do not only differ formally but also functionally.
In contrast, this article claims that the periphrasis consisting of sein + second participle has been grammaticalised in German. Although the construction had a resultative function in the Old High German period, it nowadays also refers to past situations which can be relevant to the point of speech. Therefore, its function is equivalent to the haben perfect. The reanalysis of sein + second participle is reflected by the distribution of the auxiliaries which is not strictly conditioned by aktionsart anymore. Though a corpus-based investigation of verbs of movement shows there are still restrictions for the periphrasis with sein: It is not permitted in prototypically transitive sentences. Whereas agentivity of the subject doesn't influence the auxiliary choice, sentences with prototypical objects prohibit the perfect with sein. Those objects are usually individuated or referential. Hence, they can underlie a change of state or position. Obviously, sein perfect has broken the actional restrictions, but there are still limitations concerning the argument structure. This shows that the sein periphrasis is only weakly grammaticalized.