The allotment rate of a Hong Kong IPO is not a fixed number. It depends on how many shares the public offering finally holds, how many applicants and how much capital apply, and the allotment method used. This page walks through each step in order. Figures in the example are hypothetical and do not refer to any specific IPO.
The public offering is divided by application amount: orders of HK$5 million or less go to Pool A, orders above HK$5 million go to Pool B. Each pool receives 50% of the public offer shares and is allotted separately, so the allotment rate in Pool A and Pool B of the same IPO can differ widely. The largest tier in Pool A is called A-Tail and the smallest tier in Pool B is called B-Head; they are the closest in application amount and are often compared.
At launch the public offering is only a small part of the global offering. The more oversubscribed the deal, the more shares are clawed back from the international placing to the public offering. Clawback tiers are set by the public offering oversubscription multiple and vary by offering mechanism. The table below shows common rules; the prospectus and the allotment results announcement are authoritative.
| Mechanism | Initial public offering | Clawback trigger and final share | Note |
|---|---|---|---|
| Mechanism A (from 4 Aug 2025) | 5% | 15x to under 50x: 15%; 50x to under 100x: 25%; 100x and above: 35% | No clawback below 15x |
| Mechanism A (before) | 10% | 15x to under 50x: 30%; 50x to under 100x: 40%; 100x and above: 50% | No clawback below 15x |
| Mechanism B | 10% to 60%, set by the issuer | No clawback | Public share is fixed |
| Chapter 18C specialist tech | 5% | 10x to under 50x: 10%; 50x and above: 20% | No clawback below 10x |
Large IPOs raising over HK$10 billion may be granted a waiver case by case with different clawback shares. Clawback only changes the total size of the public offering; the 50/50 split between Pool A and Pool B is unchanged.
Suppose an IPO under Mechanism A (from 4 Aug 2025) offers 100 million shares globally, with an initial public offering of 5%, or 5 million shares. The public offering receives applications for 300 million shares, 60 times oversubscribed, which falls in the 50x to under 100x tier. After clawback the public offering is 25% of the global offering, or 25 million shares.
The overall allotment ratio of the public offering is about 25 million / 300 million, roughly 8.3%. Each pool receives 12.5 million shares; dividing by each pool's applied shares gives that pool's average allotment ratio.
An average is not every applicant's result. Within a pool, tiers with different lot counts have different allotment rates, depending on the allotment method in the next section.
Clawback fixes how many shares each pool has; the allotment method decides which tiers receive them. Two common extremes: per-capita, where each successful applicant receives roughly the same number of lots regardless of how many they applied for, so large applications have a markedly lower allotment rate; and uniform, where allotment rates are similar across tiers and expected allotment grows with the lots applied for. Most IPOs fall in between. Cibo's allotment forecasts describe this curve with an allotment-method parameter α: the closer to 0, the more per-capita; the closer to 1, the more uniform.
The allotment rate of a tier is the share of applicants who are successful: successful applicants divided by applicants. The allotment ratio is the share of applied shares actually allotted: allotted shares divided by applied shares. The two coincide only in the smallest tier of one lot. Suppose, hypothetically, a tier has 357 applicants of whom 245 succeed: the allotment rate is about 68.6%, but each successful applicant receives only part of the shares applied for, so the allotment ratio may be only 34%. The allotment results announcement discloses both counts and ratios, so check which one is quoted. The definitions of allotment rate and allotment ratio on this page are Cibo's own statistical conventions and may differ from those used in HKEX allotment results announcements, prospectuses and documents of brokers or other institutions; the original announcements and documents prevail.
While an IPO is open, allotment results are not yet published. On a stock's allotment forecast page you can enter an expected subscription multiple and allotment-method parameter to see forecast rates by tier; after listing you can compare against actual results and backtests. Related pages: IPO list and per-stock forecast pages, IPO allotment history, allotment forecast backtest, IPO glossary.
Rules follow Chapter 4.14 of the HKEX Listing Rules and the amendments effective August 2025; figures for any stock are subject to its prospectus and allotment results announcement. This page explains data and rules and is not investment advice.
