Following Cyrus Mistry letter on his removal as Tata Chairman, Tata Sons expressed "deep regret" that the confidential letter was made public, adding it is "unforgivable" that Mistry tried to "besmirch" the group's image. It is "unfortunate" that only on his removal "allegations and misrepresentation of facts" were made, it added. Mistry claimed that Tata faces an $18 billion write-down.