Ousted Tata Sons chairman Cyrus Mistry is said to have ignored advice to sell up to 5% stake in its IT business, Tata Consultancy Services (TCS). The advice is said to have been given by members of Tata Trusts, the charitable bodies that own about 66% in Tata Sons, the holding company of the Tata Group.

According to unnamed sources, the members had asked Mistry to sell the TCS shares back in 2014, when the IT arm's stock price was at a high of Rs 2,800 (£33.78, $41.96) on the Bombay Stock Exchange, The Economic Times reports. They had suggested that the money raised from the stake sale could help pare some of the group's $25bn (£20.13bn) debt. It is said that selling 5% at the peak value in 2014 could have fetched Tata Sons $3bn at current exchange rates.

This is said to have been one of the factors that triggered a "trust deficit" between Mistry and the trust's members. The loss of trust is also said to have eventually led to him being ousted on 24 October.

However, sources close to Mistry have argued that the TCS stake was not sold even during Ratan Tata's tenure. Tata Sons holds nearly 74% stake in TCS, which is said to be worth about $32bn. While it is said to be considered a lifeline for Tata Sons, the asset has rarely been used.

Another concern for the trust members was said to be Mistry's over-reliance on TCS. In a roadmap for the group, he had said that TCS was expected to grow at 10% annually. The trusts were, however, not optimistic of this picture. While dividend from TCS accounted for 76% of Tata Sons' revenue in Ratan Tata's last full fiscal as chairman, its contribution increased to 91% in the fiscal ending March 2016, when Mistry was the boss. This indicated that dividend income from the rest of the Tata group companies was less and it contributed very little to the total revenues of Tata Sons, according to The Economic Times.

Another factor that led to the trust deficit included Mistry delaying informing the Tata Sons board that its subsidiary Tata Power had planned to acquire Welspun Energy's renewable power assets.

According to an unnamed source cited by Forbes India, while negotiations with Welspun had started in November 2015, the Tata Sons board was sent a note about the proposed transaction only in April 2016. The source added that the note did not include any details of the proposed transaction but instead had a presentation which said that it had identified renewable energy as a focus area, going forward.

"On June 12, 2016 the deal with Welspun was signed; and it is only after the Tata Sons board raised a hue and cry that a detailed presentation was made on June 29... Nobody questioned the merit of the transaction. But the very fact that the rest of the board of Tata Sons didn't know the details till a late stage wasn't done," the source said.