Shapoorji Pallonji Group has offered to sell up to 3% of Tata Sons back to the holding company for Rs 25,000 crore, a proposal Noel Tata presented to the Tata Sons board as the RBI presses for a public listing. SP holds 18.38% and faces Rs 3,500 crore debt due by September, while the offer values Tata Sons near Rs 8.3 trillion.