EN
A share market auction takes place when a seller fails to deliver the shares sold by the settlement date (T+1). The exchange holds an auction to get those shares and guarantee that the buyer obtains them or is reimbursed via a close-out settlement. The NSE/BSE clearing corporations (NCL/ICCL) regulate this procedure, which includes predetermined timelines, price bands, and sanctions to ensure market settlement discipline.
Key Takeaways
- Auctions are triggered due to short delivery when sellers fail to transfer shares by T+1 in the equity cash segment.
- The exchange conducts the auction on T+2 within a price band ranging from 20% below to 20% above the reference closing price.
- Defaulting sellers pay the price difference and auction penalties levied by the clearing corporation.
- If shares are not sourced, buyers receive cash compensation through a close-out settlement.
What is an Auction?
In the Indian share market, an auction happens when there's a short delivery; i.e., a seller fails to deliver shares they sold by the settlement date (T+1). To resolve this, the exchange (NSE/BSE) holds an auction session on T+2 to buy those undelivered shares from the market and deliver them to the buyer.
Read More About: NSE and BSE Meaning
What is Short Delivery?
Short delivery, also known as delivery shortage, occurs when the buyer does not receive the shares in their demat account because the seller failed to transfer them after the trade was executed.
In such cases, the buyer’s broker receives a shortage report from the clearing corporation, and the position is moved into the auction/close‑out process instead of normal payout. Brokers or broking apps generally notify buyers of short-delivery incidents via timely in‑app nudges, email, or SMS so they can track the status of their trades and settlements.
How Does the Auction Process Work?
- Auction Day
For short deliveries in normal equity settlement, the clearing corporation conducts a buy‑in auction on the day after the short delivery is identified, which, under the T+1 framework, generally falls on T+2 (the next trading day after the settlement date)
- Exchange Role
The exchange, through its clearing corporation, invites offers from eligible auction participants to sell the short‑delivered shares. Participants submit bids (quantity and price) within the permitted price band, and the exchange matches bids to procure the required quantity for settlement.
- Price Band
The auction is held within a prescribed price band, with the upper cap typically up to 20% above the relevant reference price (usually the previous close or T‑day settlement price, depending on segment and circulars).
Many brokers and market references illustrate this using upto a 20% band around the reference closing price. For example, if the stock closes at ₹100 on the reference day, the auction range may be ₹80 to ₹120.
- Settlement
- If the auction is successful, the shares are bought and delivered to the original buyer.
- The defaulting seller is debited the higher of the auction price and the valuation/reference price and must also bear any auction‑related penalties and charges.
- If the Auction Fails
If the exchange is unable to source shares in the auction (for example, because the security is in upper circuit or there are no sellers), the position is closed out in cash.
The close‑out price is typically the higher of the highest traded price between the trade day and the auction day, or 20% above the relevant closing/settlement price (as per segment‑specific rules and circulars).
In such cases, the buyer receives a cash credit instead of shares, and the defaulting seller bears the debit at this close‑out price.
- Eligibility to Sell in Auction
Only shares (fully settled) that are already credited to your demat account can be sold during the auction. T1 holdings (shares bought but not yet settled) are not eligible for sale. Additionally, investors cannot buy shares in the auction, as the exchange acts as the sole buyer in this process.
When Will the Shares be Credited After a Short Delivery?
The buyer’s demat account will receive the shares on T+2 day, following the exchange’s auction on T+1 day to recover the short-delivered quantity. The portfolio reflects the update on the T+3 day.
In case the exchange is unable to source the shares during the auction, the buyer’s Angel One account will be compensated with a cash credit based on the close-out price.
Example Scenario
Shares are purchased on Monday (T day) and are tagged as an unsettled quantity. If the shares were not delivered on Tuesday (T+1 day), the user will see a nudge on the equity screen on Wednesday (T+2 day).
The exchange procures the shares via an auction market held on the evening of Tuesday (T+1 day) and delivers them to your account on Wednesday (T+2 day). These shares will be fully settled and visible in your holdings from Thursday (T+3 day). In case there is a settlement holiday on the T+3 day, the shares will be reflected in your account on the T+4 day.
What Happens When a Seller Fails to Deliver Shares?
If a seller defaults on delivering shares, the exchange steps in to manage the shortfall by organising an auction to source the required quantity from other market participants. This process ensures that the buyer receives the shares despite the default. The auction is held on the next auction trading day (generally T+2 for equity cash), and the price range for bidding is set based on the closing price of the previous trading day (T+1), with an upper and lower limit of ±20%.
The shares acquired through the auction are delivered to the buyer's demat account on T+2 (usually Wednesday if the trade was on Monday) and reflected in the portfolio by T+3. Meanwhile, the defaulting seller is issued an auction note and must bear the financial consequences of the short delivery, including paying the price difference and penalties.
Example:
Imagine a seller sells 150 shares on Tuesday (T day) at ₹600 each. On the same day, the stock hits its upper circuit limit, and no sellers are available to fulfil the transaction, resulting in a delivery failure.
The exchange conducts an auction on Thursday (T+2) to acquire the 150 shares, once the shortfall is confirmed after settlement. Suppose the closing price on Wednesday (T+1) was ₹640. The auction price band will therefore be set between ₹512 and ₹768 (i.e., ±20% of ₹640).
Assume that during the auction, the shares are procured at ₹700.
Now, the seller must compensate for the price difference:
- Difference to be paid = (₹700 - ₹600) × 150 shares = ₹15,000
Additionally, the Clearing Corporation imposes an auction penalty of 0.05% on the valuation debit (along with 18% GST on the penalty amount), which is calculated using the closing price on T day:
- Valuation debit = ₹640 × 150 = ₹96,000
- Penalty = 0.05% of ₹96,000 = ₹48
- GST @18% on the penalty = ₹8.64
- Total penalty charge = ₹48 + ₹8.64 = ₹56.64
In this scenario, the defaulting seller must pay ₹15,056.64 in total due to the auction- ₹15,000 for the price difference and ₹56.64 as penalty charges.
Also Read: How to Invest in Share Market?
Conclusion
The auction mechanism in the stock market preserves settlement integrity when short deliveries occur. Exchanges defend buyer interests by sourcing shares through a regulated auction process or compensating buyers by close-out settlement, while penalising defaulting sellers. Understanding auction schedules, price bands, and fines enables investors to watch settlement results and prevent circumstances that may result in auctions.
