In 2008, the Reserve Bank of India shut down Sahara's savings unit.
The same year, however, two unlisted Sahara companies - Sahara India Real Estate Corp. Ltd and Sahara Housing Investment Corp. Ltd - with paid up capital of Rs 10 lakh (less than $20000) each, began raising funds through an instrument known as an optionally fully convertible debenture (OFCD).
Sahara argued the fundraising was a private placement.
The Securities and Exchange Board of India (SEBI) countered that a private placement should be for a maximum of 50 investors - not 29 million.
The Sahara companies touted lucrative investments promising, in some cases, to return three times their face value after 10 years.
They collected money "without any sense of responsibility to maintain records", the Supreme Court said.
The court has questioned just how genuine all the investors in Sahara's OFCD were, but has instructed Sahara to repay the full amount nonetheless.
If the investors cannot be located, Sahara must pay the money to the Indian government.