Monday was a big day for India’s Flipkart. Dubbed “Big Billion Day”, Flipkart aimed for record merchandise sales as part of a massive discount blitz not unlike the US’s Cyber Monday.

But just how great a success was it? TechinAsia.com journalist Malavika Velayanikal wrote “as expected, by the end of the day, Flipkart co-founders Sachin Bansal and Binny Bansal declared it a roaring success”.

“We have created history in Indian ecommerce… We got a billion hits on our site today and achieved our 24-hour sales target of US$100 million in GMV (gross merchandise value) in just 10 hours,” they announced.

But later reports show growing angst in India over the effect of the promotion with rivals claiming Flipkart was selling products below cost to damage competitors and some suppliers saying they were forced to cede margins so Flipkart could move volumes.

The Economic Times reported that Future Group criticised Flipkart’s Big Billion Day sale by releasing an advertisement saying “no deal can win the trust of a billion people and one has to earn it”.

“You can’t take the nation for granted even for a day,” said the ad.

The newspaper also reported vendor concerns they were compelled to sell products below cost.

“How can someone sell products below its manufacturing price? This is legally not allowed in the country. Someone can do such undercutting only to destroy competition. Just because they have foreign funding, they can’t kill local trade like that,” Kishore Biyani, founder of Future Group, was quoted by the Economic Times.

In March, Flipkart announced surpassing US$1 billion in GMV for the first time, a full year earlier than originally projected and seven years after it first launched. Ecommerce marketplaces use the term Gross merchandise value or GMV as a measure because their revenue is actually the commission amount from sellers. GMV is the total value of merchandise sold over a given period of time, according to TechinAsia.com.

In this case, it’s not clear whether the sales price taken into account to arrive at the $100 million GMV is the discounted price or marked price.

“Most ecommerce players will calculate GMV based on the net prices the items are sold at (including discount). Having said that, it’s always best to reconfirm this every time someone gives this number,” says Siddharth Talwar, partner at venture capital firm Lightbox.

When Amazon founder Jeff Bezos visited India last week, Flipkart’s huge billboards at the Bangalore airport, roads, and streets, advertising the “Big Billion Day”, greeted him. Bezos, in turn, grabbed eye-balls when he, in an Indian attire, got on top of a colorful lorry with a US$2 billion cheque for Amazon India.

Read more: Flipkart records $100 million sales on Big Billion Day, but at what price?