An IPO lock-in period is a SEBI-mandated window during which certain categories of pre-listing shareholders are prohibited from selling their shares post-listing. The purpose is to prevent disorderly supply hitting the market right after listing — and to ensure that early-stage investors (anchor institutions, promoters, pre-IPO backers) have skin in the game during the critical early trading period. For retail investors, understanding when each lock-in expires is one of the most reliable ways to anticipate post-listing supply pressure.
Why Do Lock-in Periods Exist?
Lock-ins serve three regulatory purposes set by SEBI under the ICDR Regulations:
- Price stability post-listing — without lock-in, anchor investors and pre-IPO holders could dump shares immediately after listing, creating a massive supply shock. Lock-ins force them to stay invested and absorb early volatility.
- Skin in the game — promoters need to prove they aren't running a "pump and exit" on the public market. The 18-month lock-in on the minimum 20% post-issue capital ensures continued alignment with public shareholders.
- Information signal — lock-ins are public information. The market knows precisely when each tranche unlocks, allowing rational price discovery rather than surprise dumps.
The 4 Lock-in Categories — Quick Comparison
| Category | Who | Lock-in Period | From When |
|---|---|---|---|
| Anchor — Tranche 1 | Anchor investors (50% of their allocation) | 30 days | Date of allotment |
| Anchor — Tranche 2 | Anchor investors (remaining 50% of their allocation) | 90 days | Date of allotment |
| Promoter — Minimum Contribution | Promoters' minimum 20% of post-issue paid-up capital | 18 months | Date of allotment in the IPO |
| Promoter — Excess Holding | Promoter shares above the 20% minimum | 6 months | Date of allotment in the IPO |
| Pre-IPO Non-Promoter | VCs, PE, angel investors, employees with pre-IPO ESOPs, founders excluding promoters | 6 months | Date of allotment in the IPO |
| Foreign Strategic Investors | Strategic investors with FDI commitments | Per FDI policy (often 1–3 years) | Date of allotment / inflow |
Anchor Investor Lock-in — 30 / 90 Day Split
Anchor investors (mutual funds, FPIs, insurance companies, pension funds) are allocated up to 60% of the QIB portion one working day before the public issue opens. Their lock-in is split into two tranches:
- 50% of anchor allocation → locked for 30 days from allotment
- Remaining 50% → locked for 90 days from allotment
This split was introduced by SEBI in 2022, building on the earlier 30-day blanket lock-in. The 90-day extension was added specifically to prevent early-exit selling that was destabilising newly listed stocks. Note: anchor investors invest at the upper price band, so they have no price discount — only allocation certainty + early access. Read our full Anchor Investor guide →
Promoter Lock-in — 18 Months and 6 Months
Promoter lock-in is structured in two layers under SEBI ICDR Regulations:
- Minimum 20% of post-issue paid-up capital held by promoters → locked for 18 months from the date of allotment in the IPO. This is the "skin in the game" lock-in. The 18-month period replaced the earlier 3-year requirement under SEBI's 2021 reforms (for IPOs where the issue object is only OFS or non-capex; the 3-year lock-in was retained for issues funding capital expenditure for a specific project — though SEBI has since further harmonised this).
- Promoter shares above the 20% minimum → locked for 6 months from allotment. This is to prevent immediate post-listing exits while still allowing some flexibility.
Pre-IPO Non-Promoter Lock-in — 6 Months
The entire pre-issue share capital held by non-promoter shareholders is locked in for 6 months from the date of allotment. This category is the broadest and includes:
- Venture Capital (VC) and Private Equity (PE) investors who funded the company before IPO
- Alternative Investment Funds (AIFs) with pre-IPO holdings
- Angel investors from earlier funding rounds
- Employees holding ESOPs exercised before the IPO (specific company ESOP terms may add additional vesting)
- Family members, founders, and other early backers who are not classified as promoters under the prospectus
The 6-month period replaced the earlier 1-year lock-in under SEBI's 2021 reforms aimed at making Indian IPOs more competitive vs alternative listing venues.
2026 Update — Pledged Shares Automation
Effective 16 March 2026, SEBI's ICDR Amendment Regulations introduced a technology-enabled mechanism to handle pledged pre-IPO shares held by non-promoters. Previously, releasing pledges before IPO listing required manual coordination with lenders, sometimes delaying the listing. Now, depositories will automatically mark pledged pre-IPO shares as "non-transferable" for the mandatory 6-month lock-in period, ensuring compliance without holding up the IPO.
For retail investors, this is a process improvement that should reduce IPO listing delays — but doesn't change the lock-in window itself.
What Happens on Lock-in Expiry?
On the day a lock-in tranche ends, the previously-locked shares become freely transferable. Owners are not required to sell — but they now can. Three patterns commonly emerge:
- 30-day anchor unlock — first half of anchor allocation becomes free. Some short-term tactical anchors (hedge funds, arbitrage AIFs) may book profits; long-only mutual funds typically hold longer. Expect mild selling pressure on the unlock day and the immediately following sessions.
- 90-day anchor + 6-month pre-IPO unlock — these are the bigger events. The combined supply from VCs, PE investors, and the second anchor tranche can create meaningful selling pressure. Stocks often trade weak for 1-2 weeks around the 6-month mark, especially if pre-IPO investors were sitting on large gains.
- 18-month promoter unlock — typically not a sell event because promoters have long-term skin in the game. But it does increase the float marginally and removes a regulatory constraint.
How Retail Investors Should Read Lock-in Expiry
Lock-in expiry is one of the most reliable signals retail investors can plan around:
- Note the lock-in expiry dates when you buy a recently listed IPO. Most brokerage platforms list these alongside the IPO data.
- Check the magnitude — a stock with 60% of float still locked at the 6-month mark faces much bigger supply unlock than one where promoters held only 30%.
- Watch the price action 2-3 weeks before unlock — savvy holders sometimes pre-empt the unlock by selling early or hedging via derivatives. Volume increases ahead of unlock are a warning sign.
- Don't panic-sell on unlock day — many high-quality companies absorb the unlock smoothly because long-term holders simply don't sell. Lock-in expiry is a supply event, not a fundamental event.
- Look for fundamental support — if the company is delivering on its growth plan, lock-in unlock supply is typically absorbed within 1-2 quarters.
Lock-in Expiry — Real Market Impact
Between December 2025 and March 2026, approximately 108 listed Indian companies saw lock-in expiries with a combined unlocking value of around Rs 3 lakh crore (~USD 36 billion) at face value. Not all of this hit the market — much was held — but it gives a sense of the scale of post-IPO supply that needs absorbing in any given period.
For individual stocks, the question isn't whether a price dip happens around unlock — it's whether the underlying business is delivering enough to justify holders staying invested through it.
Lock-in for SME IPOs vs Mainboard
The same SEBI ICDR lock-in framework generally applies to both Mainboard and SME IPOs. Specifics:
- Anchor lock-in — 30/90-day split applies to both Mainboard and SME (where SME issues have anchor allocation, which is increasingly common for larger SME IPOs).
- Promoter lock-in — 18-month minimum contribution + 6-month excess applies to both.
- Pre-IPO non-promoter lock-in — 6 months applies to both.
The main practical difference: SME IPOs have lower trading volumes, so even small post-unlock selling can move the price meaningfully. Mainboard liquidity absorbs supply more smoothly.
Common Misconceptions
- "All shares are locked-in for the full lock-in period." Wrong. Different categories have different windows. Retail investors who applied in the IPO have no lock-in at all — they can sell on listing day.
- "Lock-in expiry always crashes the price." Wrong. High-quality companies with strong fundamentals often absorb unlock supply with minimal impact. Crashes happen mostly when the business is underperforming.
- "Promoters cannot sell at all during the 18-month lock-in." Partially wrong. Promoters cannot sell their minimum 20% contribution during 18 months. Excess promoter holding has only a 6-month lock-in.
- "Lock-in is the same for all anchor investors." Wrong. Each anchor's allocation is split 50/50 — half unlocks at 30 days, half at 90 days.
How IPO Cracker Tracks Lock-in Data
For every IPO Cracker tracks, the IPO Detail page surfaces lock-in expiry dates derived from the allotment date:
- Anchor 30-day expiry — date when first half of anchor allocation unlocks
- Anchor 90-day expiry — date when second half unlocks
- Pre-IPO and Promoter excess (6-month) expiry — date when bulk of pre-IPO supply unlocks
- Promoter minimum (18-month) expiry — long-tail unlock
Use these dates as supply-event markers when planning entry / exit on listed IPO stocks.
Key Takeaways
- SEBI mandates lock-in to prevent disorderly post-listing supply and ensure pre-IPO investors stay aligned with public shareholders.
- Anchor investors: 50% locked 30 days, 50% locked 90 days from allotment. Promoters: minimum 20% locked 18 months, excess locked 6 months. Pre-IPO non-promoters: 6 months.
- Retail investors who applied in the IPO have no lock-in — they can sell on listing day.
- The biggest unlock event is usually the 6-month combined (90-day anchor tranche 2 + 6-month pre-IPO non-promoter + 6-month excess promoter).
- Lock-in expiry is a supply event, not a fundamental event — high-quality businesses absorb it; weak ones get punished.
Last updated: May 2026. SEBI ICDR Regulations governing lock-in are amended periodically; verify the current rules with the SEBI website (sebi.gov.in) before relying on specific durations for high-stakes decisions.