Ozi Amanat, president and chief investment officer of Singapore-based Spice Global, however, declined to comment on recent media reports linking the Indian billionaire's next big investment to the US media group.
"No comment," said Amanat in a response to a query.
He, however, described Forbes Media as "the world's top brand and an incredibly attractive investment proposition."
The Forbes family has asked for USD 500 million for the business magazine and web properties, the source said.
Three international bidders, including Spice Global, have valued the assets at between USD 300 million and USD 500 million, the source added.
According to media reports, German digital media company Axel Springer and Chinese conglomerate Fosun International were the other bidders.
The Forbes Media deal would be completed in about a month, said the source on condition of anonymity.
The final round of discussions was taking place on an individual basis following "blind auction" submissions by the three bidders, according to the source. The bidders have completed due diligence, the source said.
Forbes Media would put Spice Global in developed markets and expand its range of businesses, which include telecommunications, entertainment and healthcare.
Meanwhile, Spice Global has finalised a USD 250 million plan for Saket Smart Living in New Delhi as further expansion of the recently refurbished 350-bed hospital.
This would include a 1,500-bed hospital, medical research and rehabilitation centres in a complex spread over 16 acres.
The hospital, expected to be ready by the end of 2017, has a collaboration agreement with Singapore's healthcare group, Parkway Holdings.
Modi is focusing on developing smart health and smart living concepts as part of the healthcare business, which would offer internet-based and television-linked services to patients globally.
Spice Global is also preparing to start operations at two smart living centres one at Rishikesh on the banks of the Ganga in Uttarakhand and the other near Gurgaon.
Equipment and facilities would be added this year at the two complexes which have been completed, said Swati Saxena, Programme Director of G M Modi Hospital and Research Centre, a part of Spice Global.
Smart Living Centres are non-profitable establishments, she said during Spice Global's Global Citizen Forum and Smart-living conference held here over the weekend.
The region's top medical experts addressed the two-day gathering attended by Modi's business associates.