IPO Allotment Probability

How SEBI's IPO Allotment System Works

SEBI mandates a computerized lottery system for retail individual investor (RII) allotments in mainboard IPOs. The process is managed by the registrar — KFIN Technologies, Link Intime, or Bigshare Services — using a SEBI-prescribed algorithm that BSE or NSE oversees.

The retail category gets 35% of the total issue size in a mainboard IPO. Within this 35%, the minimum lot size is fixed such that the application value stays below ₹2 lakh. Every retail applicant — whether they apply for 1 lot or 13 lots — gets one lottery entry. Apply for one lot or the maximum allowed, your probability of getting at least one lot is identical.

This one-lot-per-applicant rule is what makes multiple demat account applications across family members the most effective strategy to improve allotment odds. It's completely legal. SEBI allows one application per PAN, so a family of four can submit four separate applications and quadruple their collective probability.

Category-Wise Quota Breakdown

Every mainboard IPO splits its shares across three categories. Each category has separate subscription tracking and separate allotment rules.

The Oversubscription Math

If the retail category receives exactly 35% of applications the IPO deserves, everyone gets allotment. But popular IPOs routinely see 50x, 100x, even 200x oversubscription in the retail bucket.

When oversubscription exceeds the number of applicants, SEBI requires the registrar to first ensure every applicant gets one minimum lot. Remaining shares — if any — go into a second round of lottery for additional lots.

Here's the math: if an IPO has retail quota for 10,00,000 lots and receives 50,00,000 valid applications, roughly 1 in 5 applicants will get allotment. Your probability is 20%. Five family members applying independently have a 67% chance that at least one of them gets allotment (using 1 - 0.8^5). This is why large families in Gujarat and Rajasthan are known to mobilize 20-30 demat accounts during hot IPOs.

NII / HNI Category — Pro-Rata Allotment

HNI investors applying above ₹2 lakh don't participate in a lottery. They get pro-rata allotment — if the HNI category is subscribed 200x and you applied for ₹20 lakh worth, you get roughly 1/200th of that, or about ₹10,000 worth of shares. The rest of your application money (blocked via ASBA) gets released.

This makes HNI applications far less capital-efficient for listing-gain seekers. Large broking houses offered IPO financing at 12-15% annual interest for HNI applications during the 2021 bull run. With pro-rata allotment in a 200x subscribed IPO, the cost of carry often exceeded the listing gain — many HNI applicants lost money after interest costs.

The NII sub-categories introduced in Budget 2022 split HNI into sNII (₹2–10 lakh) and bNII (above ₹10 lakh), each with separate quotas. This partly addressed the financing game but hasn't eliminated it.

What Actually Affects Your Allotment Probability

Three factors drive your allotment odds in the retail category: total subscription level, the number of valid retail applications, and whether the IPO lot count is sufficient to cover all applicants with at least one lot.

Applying from a bank account linked to ASBA — State Bank, HDFC, ICICI, Axis — versus using UPI through Zerodha, Groww, or PhonePe makes no difference to allotment probability. Both methods are equally valid under SEBI rules since 2019. UPI applications with ₹2 lakh limit apply only to retail category.

Common myths: applying late in the IPO window does not improve odds. Applying through the lead manager's portal does not give preference. Using a cut-off price bid is mandatory for retail applicants and gives no edge. The only real edge is the number of valid PAN-based applications you can generate across your family.