Under the offer, the company plans to issue fresh shares worth Rs 1,272 crore. An equivalent amount can be raised through sale of up to 3.01 crore shares by its existing shareholders.
Citigroup, JPMorgan India, Morgan Stanley, Barclays, UBS Securities India and Kotak Mahindra Capital Company are managers for the share sale.
Without disclosing the details of clarifications sought, the Securities and Exchange Board of India (Sebi) said it is awaiting response from the lead manager for the proposed public offer.
The next update will be uploaded on Sebi's website on August 10.
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The market watchdog said it issues observations on draft offer document within 30 days after receiving a satisfactory reply from the lead merchant banker regarding the clarification or additional information sought from it.
Sebi had earlier also sought clarification on the IPO of InterGlobe Aviation, which runs the country's biggest airline by market share under the IndiGo brand.
IndiGo is one of the two profit-making domestic airlines. The only other profitable airline is GoAir.
The already-listed airlines in the country include Jet Airways and SpiceJet while trading in long-grounded Kingfisher Airlines has been suspended for a long time due to penal reasons.
Last month, Sydney-based aviation think-tank Centre for Asia Pacific Aviation (CAPA) had said IndiGo is estimated to have recorded a profit of USD 150-175 million in 2014-15.
The low-cost model using a single type of narrow-body planes is one of the contributing factors for IndiGo's profitability.