On listing day, everyone who was allotted shares in the public portion of an IPO is free to sell. But a large block of shares is not — those held by promoters, certain pre-IPO investors and anchor investors. This restriction is called the lock-in period. Knowing who is locked in, and when the lock-in ends, helps you read the share supply picture around an IPO without guessing.
Key Takeaways
- Lock-in is counted from the date of allotment, not the listing date.
- Different holders have different lock-ins: promoters, pre-IPO investors and anchors are each treated separately.
- SME IPOs use longer lock-ins than mainboard IPOs.
- Lock-in expiry increases the shares eligible to trade; it does not force anyone to sell.
- Retail, NII and non-anchor QIB allottees are not locked in at all.
Why Do Lock-in Periods Exist?
Regulators want people who built or funded the business to stay invested for a period after the company raises public money. If insiders could sell immediately after listing, public investors would bear the risk while early holders exited. Lock-ins also reduce sudden supply of shares in the days right after listing, when price discovery is still settling.
Mainboard IPO Lock-in Rules
| Shareholder | What is locked | Lock-in period (from allotment) |
|---|---|---|
| Promoters | Minimum promoters' contribution — 20% of post-issue capital | 18 months (3 years where most fresh-issue proceeds fund capital expenditure) |
| Promoters | Holding above the 20% minimum contribution | 6 months (1 year in the capex case) |
| Pre-IPO non-promoter holders | Pre-issue shares held by other investors | 6 months (certain categories have their own exemptions or conditions) |
| Anchor investors | 50% of anchor allotment | 30 days |
| Anchor investors | Remaining 50% of anchor allotment | 90 days |
| Retail / NII / non-anchor QIB allottees | Shares allotted in the public offer | No lock-in |
These periods were shortened by a 2022 amendment to the ICDR regulations; earlier rules locked the promoters' minimum contribution for 3 years and excess holdings for 1 year. Note that "promoters' minimum contribution" means the promoters must hold at least 20% of the post-issue capital, and that block is the one under the longest lock-in.
SME IPO Lock-in Rules
SME platforms apply longer restrictions, reflecting the higher risk profile of smaller issuers. As summarised in a May 2026 legal commentary on the ICDR framework:
| Shareholder | Lock-in period |
|---|---|
| Promoters' minimum contribution (20%) | 3 years (from the later of allotment and commencement of commercial production, where applicable) |
| Excess promoter holding | Released in stages — first 50% after 1 year, remaining 50% after 2 years from allotment |
| Pre-IPO non-promoter holders | 1 year from allotment |
| Anchor investors | 30 days for 50% and 90 days for 50% |
A March 2026 amendment also addressed pre-IPO shares that are pledged: depositories must mark them as non-transferable for the full lock-in period, so pledging cannot be used to sidestep the restriction. Rules are amended periodically, so treat this table as a snapshot and verify it against the offer document.
A Worked Calendar Example
Suppose a mainboard IPO's shares are allotted on 10 October. The locks would run like this (illustrative dates):
| Group | Lock-in ends |
|---|---|
| Anchor investors — first 50% | 9 November (30 days after 10 October) |
| Anchor investors — remaining 50% | 8 January (90 days after 10 October) |
| Pre-IPO non-promoter holders and excess promoter shares | 10 April (6 months after allotment) |
| Promoters' minimum contribution (20%) | 10 April, one year after the 6-month date (18 months after allotment) |
What Actually Happens When a Lock-in Expires?
When a lock-in ends, the shares become eligible for sale and, in practice, more shares can come into the market. That is all the rule guarantees. Holders may continue to hold, sell in parts, or sell at once. Some market participants track expiry dates as a supply factor, but the effect on price depends on the holder's plans, market conditions and demand at that time — it is not a predictable outcome, and this article makes no forecast.
How to Find Lock-in Details for a Specific IPO
- Offer document (DRHP/RHP): the capital structure chapter lists which shares are locked in and for how long. See our guide to reading the DRHP and RHP.
- Anchor allotment disclosure: published by the exchanges one working day before the issue opens, giving the amount and names — read more in our anchor investor guide.
- Post-listing shareholding pattern: filed with NSE and BSE, it shows how many shares are locked in at each quarter-end.
Lock-in and the Fresh Issue / OFS Split
Lock-in interacts with how the IPO is structured. Shares sold in an offer for sale are, by definition, being sold by the seller and end up with public investors. Only the shares the promoters and other holders retain are locked in. To see how much the promoters are selling versus retaining, read the split explained in our article on fresh issue vs offer for sale.
Do Lock-in Rules Affect Retail Investors Directly?
Not for your own shares — allottees in the public portion can sell on listing day, and tax treatment is covered in our note on tax on IPO listing gains. Lock-in matters mainly as background for understanding who else can sell, and when. Our guide on selling IPO shares on listing day explains the practical steps.
Frequently Asked Questions
Sources & Further Reading
- SEBI — ICDR Regulations (minimum promoters' contribution and lock-in provisions)
- Mondaq — Decoding the IPO lock-in framework under the SEBI ICDR Regulations (May 2026)
- NSE India — shareholding patterns and lock-in disclosures
- BSE India — shareholding patterns and lock-in disclosures
Rules and limits in India's IPO market are revised from time to time. This article was last reviewed on September 19, 2026; confirm the current position on sebi.gov.in and in the offer document of the specific issue before relying on any number here.
