What is Kostak Rate?
Kostak rate is the price at which an IPO application form is bought or sold in the grey market (unofficial, off-exchange market) before the IPO allotment is announced. When you sell your IPO application at "Kostak," you are selling the entire application — along with the right to any shares that may be allotted — to a buyer in the grey market. In return, you receive a fixed cash payment regardless of whether you actually get allotment or not.
For example, if the Kostak rate for an IPO is Rs 1,500, a buyer will pay you Rs 1,500 for your application. If you get allotted shares, you must transfer those shares to the buyer after they are credited to your demat account. If you do not get allotment, you keep the Rs 1,500 and the buyer bears the loss. The Kostak rate represents the buyer's assessment of the expected profit from the IPO, discounted by the probability of getting allotment.
Kostak rates vary significantly across IPOs. For highly anticipated IPOs with strong Grey Market Premium (GMP), the Kostak rate can be Rs 2,000 to Rs 10,000 or more per application. For average IPOs with moderate demand, the Kostak rate may be Rs 200 to Rs 500. For IPOs with weak demand or negative GMP, there may be no Kostak market at all.
The word "Kostak" has its origins in the Gujarati trading community and has been part of Indian stock market jargon for decades. It is sometimes also spelled "Kostek" or "Costuck" in different regional variations.
Kostak vs GMP — Key Difference
While Kostak and GMP (Grey Market Premium) are both grey market indicators, they measure fundamentally different things and should not be confused:
GMP (Grey Market Premium) is the premium at which IPO shares are being traded in the grey market before listing. It reflects the expected listing price of the stock. For example, if the issue price is Rs 300 and GMP is Rs 50, the grey market expects the stock to list at approximately Rs 350. GMP applies to shares — it is a per-share premium.
Kostak is the price for the entire application form, not individual shares. It factors in both the expected listing gain (GMP) AND the probability of getting allotment. An IPO might have a very high GMP of Rs 100 per share, but if the retail subscription is 50x (meaning only 1 in 50 applicants will get allotment), the Kostak rate will be much lower than you might expect because the buyer is paying for an uncertain allotment.
Mathematical relationship: In theory, Kostak rate = (Expected listing gain per lot) × (Probability of allotment). If an IPO has a GMP of Rs 50, lot size of 100 shares, and expected allotment probability of 10 percent, the expected Kostak would be approximately (50 × 100) × 10% = Rs 500. In practice, Kostak rates deviate from this formula due to market sentiment, supply-demand dynamics, and the risk preferences of grey market participants.
The key practical difference is that GMP changes continuously — it can rise or fall until listing day. Kostak, however, is a fixed deal — once you sell your application at a Kostak rate, the price is locked regardless of what happens to GMP, allotment, or the actual listing price.
How Kostak Works in Practice
Here is a step-by-step walkthrough of a typical Kostak transaction:
Step 1 — You apply for the IPO. You apply through your broker's platform (Zerodha, Groww, Upstox, Angel One, etc.) using your UPI ID. Your application is submitted through ASBA (Application Supported by Blocked Amount), which means the application money is blocked in your bank account but not debited.
Step 2 — You find a Kostak buyer. This happens through informal channels — local broker offices, Telegram groups, WhatsApp groups, or through known grey market dealers. The Kostak rate is negotiated based on the current GMP, expected subscription levels, and the buyer's own assessment.
Step 3 — You agree on the Kostak price. Let us say the Kostak rate is Rs 1,500 for a retail application of one lot. You and the buyer agree on this price, usually with a verbal commitment or an informal written note.
Step 4 — The buyer pays you. This is where it gets informal. Payment is typically made in cash, through UPI transfer, or via an intermediary. There is no formal contract, no receipt, and no regulatory oversight. This is purely a trust-based transaction.
Step 5 — Allotment happens. After the IPO subscription closes and the registrar completes the allotment process, there are two outcomes:
- If you get allotment: The shares are credited to your demat account. You must then sell these shares (typically on listing day) and transfer the sale proceeds minus the issue price to the buyer. Alternatively, you can transfer the shares via an off-market transfer.
- If you do not get allotment: The transaction is complete. You keep the Kostak money (Rs 1,500) and the buyer bears the cost. Your blocked ASBA amount is released back to your bank account.
What is Subject to Sauda (SS)?
Subject to Sauda (often abbreviated as SS) is a variation of the Kostak trade with one crucial difference: the deal is contingent on you getting allotment. With a regular Kostak deal, you get paid regardless of allotment. With Subject to Sauda, you only get paid if you actually receive shares.
How SS works: If the Subject to Sauda rate is Rs 8,000 for an IPO and you sell your application "Subject to Sauda," you will receive Rs 8,000 only if you get allotment. If you do not get allotment, neither party pays anything and the deal is void.
Why SS rates are higher than Kostak: Since the buyer only pays if allotment is confirmed, the SS rate is always higher than the Kostak rate for the same IPO. The buyer takes less risk (paying only when shares are guaranteed), so they are willing to pay a higher price. If Kostak is Rs 1,500, the SS rate for the same IPO might be Rs 8,000 to Rs 12,000.
When to prefer Kostak vs SS: If you want guaranteed money regardless of allotment, choose Kostak. If you are confident the IPO will deliver strong listing gains and you believe the SS rate is high enough to capture most of that gain with certainty, choose Subject to Sauda.
Is Selling Kostak Legal?
This is the most common question about Kostak trading, and the answer requires nuance. Selling your IPO application in the grey market through Kostak is not specifically illegal under Indian law in the sense that there is no law that explicitly prohibits it. However, it exists in a legal grey area:
SEBI does not recognise or regulate Kostak transactions. These deals happen entirely outside the regulated exchange framework. They are not recorded, not taxed (unless voluntarily declared), and not enforceable through legal channels.
No legal recourse. If the buyer refuses to pay after you have been allotted shares and transferred them, you have no legal remedy. Similarly, if you sell your application at Kostak but then refuse to transfer the allotted shares to the buyer, the buyer cannot take legal action against you. These transactions operate entirely on trust and reputation within grey market dealer networks.
Tax implications. Income from Kostak transactions is technically taxable — it falls under "income from other sources" or "business income" depending on frequency. However, since these transactions are cash-based and undocumented, they frequently go unreported. Not reporting this income is a tax compliance violation.
SEBI's stance. SEBI has periodically warned investors against participating in the IPO grey market. While SEBI has not taken direct enforcement action against Kostak trading, it has investigated and penalised grey market operators who manipulated IPO demand or subscription numbers.
When Does Selling Kostak Make Sense?
There are specific situations where selling your IPO application at Kostak is a rational decision:
When the Kostak rate locks in a satisfactory profit. If you applied for an IPO hoping for a Rs 3,000 listing gain and the Kostak rate is Rs 2,000, you are capturing two-thirds of your expected profit with zero risk. This is particularly appealing when allotment probability is low — why take a 5 percent chance at Rs 3,000 when you can take a guaranteed Rs 2,000?
When market conditions are deteriorating. If the broader market has fallen sharply between the IPO subscription period and the expected listing date, GMP may drop significantly. Selling Kostak during the subscription period locks in a price that was set during more optimistic market conditions.
When you need the capital freed up. ASBA blocks your application money for 6-8 days. If you need that capital for another opportunity (another IPO, a market dip to buy stocks), selling Kostak and forgoing the allotment upside can free up capital sooner.
When subscription levels are extremely high. If the retail category is subscribed 50x or more, your allotment probability is approximately 2 percent. A guaranteed Kostak payment is often more rational than a 2 percent shot at listing gains.
Risks of Selling Kostak
Despite its appeal, Kostak trading carries significant risks:
- Counterparty default. The buyer may refuse to pay after you have committed. Since there is no legal contract, you have no recourse.
- Trust-based networks. Kostak deals depend on personal networks and reputation. Newcomers are particularly vulnerable to being cheated by unscrupulous operators.
- Regulatory risk. SEBI could crack down on grey market activity at any time. Participants could face penalties or have their trading accounts scrutinised.
- Tax risk. Unreported Kostak income is a tax violation. If the Income Tax Department investigates your financial transactions, unexplained cash credits can attract penalties.
- Emotional regret. If you sell Kostak at Rs 2,000 and the actual listing gain turns out to be Rs 15,000, the regret can be significant. This is especially common in SME IPOs that occasionally deliver massive listing gains.
Current Kostak Trends
In 2025 and 2026, the Kostak market has evolved significantly. Several trends are worth noting:
Digital Kostak. Increasingly, Kostak deals are negotiated through Telegram groups and specialised WhatsApp communities rather than through physical broker offices. This has expanded access but also increased the risk of dealing with unknown counterparties.
Rising Kostak rates. As more retail investors become aware of the Kostak market, rates have generally increased. For hot IPOs, Kostak rates of Rs 5,000 to Rs 15,000 per application are no longer uncommon, reflecting the strong IPO market and high GMP levels.
SME Kostak premium. SME IPOs often command disproportionately high Kostak rates relative to their issue size because the large lot sizes and high minimum investments mean fewer retail applications, increasing allotment probability and expected per-application returns.
Seasonal variation. Kostak rates tend to be higher during bullish market phases (October-March) and lower during monsoon season (July-August) when the IPO pipeline typically slows down and market sentiment is more cautious.
Key Takeaways
- Kostak is the price for selling your entire IPO application in the grey market — you receive a fixed amount regardless of whether you get allotment or not
- Subject to Sauda (SS) is the payment for your application only if you get allotment — SS rates are always higher than Kostak rates for the same IPO
- Kostak rate is not the same as GMP — Kostak factors in both the expected listing gain AND the probability of getting allotment
- Kostak trading is not specifically illegal but operates in a legal grey area — there is no regulatory oversight, no legal recourse for disputes, and undeclared income is a tax violation
- Selling Kostak makes sense when the rate locks in a satisfactory profit, market conditions are deteriorating, allotment probability is very low, or you need your capital freed up for other opportunities
- The primary risks are counterparty default (buyer refuses to pay), regulatory risk (potential SEBI crackdown), and opportunity cost (missing out on higher listing gains)
- Always deal with trusted, known grey market participants if you choose to engage — never transact with anonymous online operators
Disclaimer: This article is published by ipomarket.in for educational and informational purposes only. It does not constitute investment advice, a recommendation to buy or sell any security, or an offer to invest. IPO investments are subject to market risks. Grey Market Premium (GMP) data is sourced from unofficial market participants and is not endorsed by SEBI, NSE, or BSE. Past performance is not indicative of future results. Please read all scheme-related documents carefully and consult a SEBI-registered financial advisor before investing. ipomarket.in is not a SEBI-registered investment advisor or research analyst.