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Guide· 8 min read

Anchor Lock-In Expiry Impact: 30-Day vs 90-Day Free-Float Release & Post-Listing Volume Study

When anchor lock-ins expire, millions of shares unlock for trading. We analyze the 30-day and 90-day supply shock patterns and how smart investors trade them.

ED
Editorial Research DeskPrimary Market Desk

Published on 2026-08-29 · Verified Analysis

SEBI Regulatory & RED Audited
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Editorial Key Takeaways

This analysis is based on official Draft Red Herring Prospectus (DRED) filings, historical peer valuation multiples, and exchange data. Figures are audited for institutional accuracy.

In This Article

  1. 1.1. The SEBI 50:50 Anchor Lock-in Architecture
  2. 2.2. The Supply Shock Mechanism: What Happens on Unlock Days?
  3. 3.3. High-Conviction Strategy for Retail Investors

Anchor Investor Lock-In Expiry: 30-Day vs 90-Day Analysis

Under SEBI regulations, institutional investors allocated shares in the Anchor Investor Quota (allotted one day prior to the public IPO open date) are subject to mandatory trading lock-in periods to prevent immediate dumping on listing day.

In April 2022, SEBI revised the anchor framework from a simple 30-day lock-in to a bifurcated 30-day and 90-day schedule. This guide explains the mechanics of anchor lock-in releases, the resulting supply shocks, and historical post-expiry price action.

1. The SEBI 50:50 Anchor Lock-in Architecture

When a company raises anchor capital:

  • 50% of the Anchor Allocation: Locked in for 30 Days from the date of allotment.
  • Remaining 50% of the Anchor Allocation: Locked in for 90 Days from the date of allotment.

    • Why SEBI Introduced This:

    Previously, 100% of anchor shares hit the market simultaneously on Day 31, causing severe price volatility and panic selling in newly listed stocks (e.g., Paytm, Zomato, Nykaa). Staggering the unlock into two 50% tranches smooths secondary market liquidity.

    2. The Supply Shock Mechanism: What Happens on Unlock Days?

    ```

    Day T: Listing Day (Anchors Frozen) -> Day T+30: 50% Anchor Shares Unlocked -> Day T+90: Remaining 50% Anchor Shares Unlocked

    ```

    On the morning of the 30-day and 90-day expiry dates:

    1. Free-Float Expansion: The actively tradeable floating shares in the market suddenly increase by 20% to 50%.

    2. Short-Term Price Pressure: Anchor funds seeking to rebalance or book quick profits place market sell orders, leading to temporary price drops of 2% to 6% around the opening bell.

    3. Institutional Absorption: Quality fundamental stocks witness high institutional buying absorption, where mutual funds use the anchor unlock dip to accumulate large positions without moving the market price upward.

    3. High-Conviction Strategy for Retail Investors

  • Avoid Buying 2–3 Days Before Lock-In Expiry: If a recently listed stock is trading near an anchor unlock date, wait for the supply absorption before entering fresh positions.
  • Check Anchor Quality: If the anchor book is dominated by long-only sovereign wealth funds (GIC, ADIA, Temasek) and domestic mutual funds, selling pressure is minimal. If dominated by hedge funds, expect heavy profit-taking.

    • Track upcoming anchor allocation announcements on our [IPO Calendar](/calendar).

    *Disclaimer: This analysis is for educational purposes only.*

    ED

    About Editorial Research Desk

    Primary Market Analyst & Senior Financial Journalist · IPO Latest Updates Daily

    Our research desk specializes in reading SEBI Red Herring Prospectuses, institutional anchor allocations, and forensic balance sheet audits. Every report follows rigorous E-E-A-T research standards without promoter sponsorship.