India's No. 1 software services firm, Tata Consultancy Services (TCS), a majority-owned unit of Tata Sons, said on Thursday it received a letter from Tata Sons nominating Ishaat Hussain as interim chair of TCS in place of Cyrus Mistry.

Last month, Mistry was ousted as chairman of Tata Sons in a surprise move, and was replaced by Ratan Tata as interim chair. A similar move to unseat Mistry from TCS, the crown jewel in the Tata conglomerate portfolio, was anticipated given the bitter war of words that has erupted between the two sides following Mistry's ouster.
With Tata Sons controlling an over 70 percent stake in TCS, lawyers had noted that removing Mistry as chair of the software and services company, would be a much easier task than removing his as chair of many other ventures that Tata Sons do not own a majority stake within.
"Mistry has ceased to be the Chairman of the Board of directors of the company, and Hussain is the new Chairman of the company," TCS said in a securities filing, adding Hussain will remain TCS chairman until a permanent new replacement is named.
Meanwhile, Tata Sons has called for an extraordinary general meeting of shareholders to consider a resolution for removal of Mistry as TCS director.
Hussain, a director of several Tata companies, including Tata Steel and air conditioning and engineering arm Voltas Ltd, currently serves as chairman of Voltas and satellite television provider Tata Sky.
Mistry's ouster has triggered a public spat between him and Tata Sons, which has also pushed some of Mistry's closest aides out of the group.
Mistry, whose family controls an 18.41 percent stake in Tata Sons, continues to be the chair of some of the key listed group companies such as Indian Hotels, Tata Motors and Tata Steel.
Tata Sons owned a 73.26 percent stake in TCS, as of Sept, 30, according to exchange data. Shares of Tata Consultancy Services are down some 11 percent this year up to Wednesday's close.