Tata Trusts stood firm on its ground to reject the Shapoorji Pallonji (SP) Group’s proposal to transfer its 18.4 per cent stake in Tata Sons as collateral for fresh loans, as reported by the Mint newspaper. Tata Trusts' chief executive officer Siddharth Sharma informed that Tata Sons shares are not freely transferable according to the company’s Articles of Association, the report stated.