Zakat is compulsory on any asset acquired with the intention of trading. Ibn Munzir has reported a consensus of scholars on this.
However, the Zaahriyas, Imam Showkani and Sheikh Albani differed with the others and consider that trading stock are not zakatable. These scholars argue that there is a lack of clear Quranic verses or authentic hadith that say zakat is payable on trading stock.
And Allah knows best!
(Mufti) Billal Omarjee