Which Sura is equivalent to half of the Qur'an?

There is no authentic evidence that a specific surah is equivalent to half of the Quran. Weak hadiths have been reported stating that Surat Az-Zalzalah is equivalent to half of the Quran, and that Surat Al-Ikhlas is equivalent to half of the Quran. However, what is established regarding Surat Al-Ikhlas is that it is equivalent to one-third of the Quran.