From the latest issue of monthly manga magazine "Shounen Ace", it was announced that manga "Suzumiya Haruhi no Yuuutsu", adapted from the light novel of the same name, will have its final chapter in the next issue which will be published on September 26th. The manga started serialization in late 2005 and so far 19 volumes have been published. Since the manga has caught up to the light novel, it is thought that the main reason for the manga's end is due to a lack of source material.

Source: Scan of Shounen Ace via 0taku