Walmart-owned Flipkart and Amazon dominated 90 per cent of the market share during the six-day sale event, said Bengaluru-based research firm RedSeer Consultancy.
Given the momentum seen in the first edition of the festive sale, the entire month of October is expected to generate up to $6 billion (Rs 39,000 crore) in online sales, almost shared by Amazon and Flipkart.
"The first wave of the festive sale event has seen record GMV of almost $3 billion despite the challenging macro environment, indicating that consumer sentiment on online shopping remains bullish," said Anil Kumar, Founder, and CEO, RedSeer Consulting.
The year-on-year (YoY) growth during the festive sale period was 30 per cent, with significant share coming from customers in tier II and III cities.
Mobile was the category leader, contributing to over 55 per cent of GMV in festive days. Consumers delayed their mobile purchases for the festive sale season, indicating the strong "value shopping" proposition of festive days.
Flipkart continued to lead the festive sales in GMV terms, with 60-62 per cent standalone Gross GMV share during the sale event, and nearly 63 per cent share if other group entities (Myntra and Jabong) are also included, said the report.
"Strong performance across categories including mobiles was the key reason for Flipkart leadership. This was, in turn, enabled by strong value prices, high EMIs adoption and diverse selection across categories, all marketed aggressively to reach customers widely," the RedSeer report said.
Amazon's GMV growth was 22 per cent (YoY). However, its volume growth rate was more than 30 per cent (YoY).
"The larger push has come from Bharat customers, migrating to online shopping driven by the strong value provided from the online retailers across categories including mobiles, which have shown a strong surge during sale event despite having a relatively slow growing first half of 2019," Kumar noted.
Earlier, two big e-commerce players Amazon.in and Flipkart announced record transactions on their respective platforms, along with adding new customers, especially from the tier II and III cities in the September 29-October 4 sale period.
Consumer electronics, smartphones, fashion and large appliances were among the top gainers as the demand surged from smaller cities and towns this year -- indicating that the consumer spending has only increased in the country despite slowdown fears.
Amazon.in said it received orders from 99.4 per cent of pincodes while over 65,000 sellers from more than 500 cities received orders in just five days of the first edition of its "Great Indian Festival" sale.
Nearly 15,000 sellers more than doubled the sales while millionaire sellers including "crorepati" sellers exceeded 21,000 sellers in the sale.
Aiming to bring the next 200 million consumers to the e-commerce fold, Flipkart said that "The Big Billion Days" sale witnessed almost 50 per cent growth in the number of new customers compared to last year, with 70 billion views in six days of the sale.
Clocking record sales powered by shoppers and sellers from tier 2 cities and beyond, more than 50 per cent of Flipkart Plus shoppers were from smaller cities and towns, while sales from tier 3 cities grew by 100 per cent (YoY).
Nearly 50 per cent of top sellers on Flipkart witnessed 3X growth and over 40 per cent of transacting sellers during the sale were from Tier 2 and beyond towns.