Pool A/B Comparison

Pool A/B data comparison for 301 IPO stocks

Summary Statistics

301
Covering 301 IPO stocks
272 (90%)
B-Head gets more lots
29 (10%)
A-Tail gets more lots
+22.0%
Overall avg first-day return
Stocks with first-day data: 258
By Offering Mechanism: 机制A(旧): 132 机制B: 142 未知: 1 机制A: 9 18C特专科技: 17
Bar colors: teal = B-Head prevails, pink = A-Tail prevails; dots at bar tops = offering mechanism (● Mech B teal ● Mech A pink ● Exempt purple); dashed line = parity (1.0x)

Pool A/B Comparison Charts

◆ Mechanism B ● Mechanism A ▲ Mechanism A (Old) ◼ Large IPO Exemption ⌖ 18C Specialist Tech = Offering Mechanism (dots at bar tops)

A-Tail vs B-Head — Expected Allotment Lots Ratio ■ B-Head prevails ■ A-Tail prevails

In HK IPOs, the public offering is split by subscription amount into Pool A (smaller subscriptions, typically ≤HK$5M) and Pool B (larger subscriptions, typically >HK$5M). A-Tail refers to the highest subscription tier within Pool A, and B-Head refers to the lowest subscription tier within Pool B. This chart compares the expected allotment lot ratio between A-Tail and B-Head. Redder = B-Head advantage (B-Head lots > A-Tail), more purple = A-Tail advantage (A-Tail lots > B-Head). Data calculated from allotment results announcements published by share registrars.

A-Tail vs B-Head — Capital Efficiency Ratio (Considering Frozen Capital Cost) ■ B-Head more efficient ■ A-Tail more efficient

Capital efficiency ratio comparing A-Tail/B-Head efficiency after accounting for frozen capital costs. See above for Pool A/B explanation. A-Tail frozen capital = A-Tail subscription lots × per-lot amount. B-Head frozen capital = B-Head subscription lots × per-lot amount. Freeze duration based on expected settlement dates disclosed in the prospectus. Redder = B-Head more efficient, more purple = A-Tail more efficient.

Pool A vs B Applicant Distribution (Time Series)

Diverging bar chart showing Pool A vs B applicant distribution for each IPO. The X-axis lists stocks in reverse chronological order (newest first), with linear scale on the Y-axis. Pool A bars (red) extend upward, Pool B bars (purple) extend downward, revealing the real scale asymmetry between the two tranches over time. Data calculated from allotment results announcements published by share registrars.

Pool A vs B Fund Distribution (Time Series)

Diverging bar chart showing Pool A vs B fund distribution for each IPO. The X-axis lists stocks in reverse chronological order (newest first), with linear scale on the Y-axis. Pool A bars (red) extend upward, Pool B bars (purple) extend downward. Note that Pool B funds often far exceed Pool A, as Pool B represents high-net-worth and institutional investors placing much larger individual subscriptions. Data calculated from allotment results announcements published by share registrars.

Pool A/B Rules & Investor Education

This page aggregates Pool A and Pool B data from all HK IPOs with publicly available allotment details, presenting the differences through four interactive charts. Whether you're new to IPO subscription or an experienced investor, understanding how Pool A/B works can help you make more informed subscription decisions.

1. What Are Pool A and Pool B?

Under HKEX Listing Rules, the Public Offer tranche is split into Pool A and Pool B based on subscription amount:

Pool A: Subscription orders of HK$5 million or below. Pool A typically represents retail investors and small-to-medium subscriptions.

Pool B: Subscription orders exceeding HK$5 million. Pool B represents high-net-worth individuals, professional investors, and institutional investors.

HK$5 million is the threshold separating Pool A from Pool B. This threshold was formalized by HKEX upon the launch of the FINI platform. Both tranches follow the same clawback mechanism, but due to the significant difference in subscription size, the allotment rates and capital efficiency between the two groups often differ materially.

A-Tail: The highest subscription tier within Pool A, i.e., the tier closest to the HK$5M threshold.
B-Head: The lowest subscription tier within Pool B, i.e., the tier just crossing the HK$5M threshold.

A-Tail and B-Head are closest in subscription amount and form the core comparison pair for allotment rates and capital efficiency. The first two charts on this page are dedicated to comparing these two tiers.

2. Key Terminology

TermChineseDefinition
Pool A甲组Subscription tiers with amount ≤ HK$5M, representing the lower end of the public offer
Pool B乙组Subscription tiers with amount > HK$5M, representing the upper end of the public offer
A-Tail甲尾The highest subscription tier within Pool A, closest to the HK$5M threshold
B-Head乙头The lowest subscription tier within Pool B, just above the HK$5M threshold
Expected Allotment Lots期望中签手数The expected number of allotted lots at a given subscription tier, calculated as: Allotment Ratio × Subscribed Shares / Lot Size
Frozen Capital冻结资金Funds temporarily locked during IPO subscription. Freeze duration is based on the expected settlement dates per the prospectus. This is an implicit cost of IPO subscription
Capital Efficiency资金效率Expected allotment lots per HK$10,000 of frozen capital (lots/10K HKD). A higher value means more lots per unit of capital committed
Oversubscription Ratio超额认购倍数Total public offer subscription amount / initial offering size, reflecting market demand for the IPO
Allotment Ratio配发比率The percentage of subscribed shares actually allotted at each tier, determined by the clawback mechanism and allotment algorithm

3. How to Read the Four Charts

Chart 1: A-Tail vs B-Head — Expected Allotment Lots Ratio
Compares expected allotment lots between A-Tail and B-Head for each IPO. The Y-axis shows the deviation multiple: B-Head prevails means B-Head gets more lots than A-Tail (ratio > 1); A-Tail prevails means A-Tail gets more lots (ratio < 1, shown as reciprocal). The dashed line at y=1 represents parity. Use the zoom slider to explore earlier IPOs.

Chart 2: A-Tail vs B-Head — Capital Efficiency Ratio
Building on expected lots, this chart incorporates frozen capital cost. Capital efficiency = expected lots / frozen capital (per 10K HKD). For the same allotment outcome, more frozen capital or longer freeze periods reduce efficiency. This chart helps investors balance allotment rates against the opportunity cost of locked funds.

Chart 3: Pool A vs B Applicant Distribution (Time Series)
Diverging bar chart showing applicant counts per IPO. Pool A (red) extends upward, Pool B (purple) extends downward. Time trends reveal: both groups increase during market booms; Pool A consistently outnumbers Pool B (larger retail base); larger IPOs see higher Pool B participation.

Chart 4: Pool A vs B Fund Distribution (Time Series)
Same mirror structure as Chart 3, but showing total subscription funds. Note that Pool B funds often dwarf Pool A (as Pool B consists of high-net-worth/institutional investors placing much larger orders), visually demonstrating the structural feature of public offers where "a few large orders account for the majority of funds."

Important: The A-Tail vs B-Head comparison reflects the difference between tiers just below and just above the HK$5M threshold. Since different IPOs may have different tier structures, the specific subscription amounts for A-Tail and B-Head can vary by IPO. The data on this page is for educational reference only and does not constitute investment advice.

The educational content on this page is based on publicly available HKEX rules. Chart data is derived from HKEX allotment results announcements. Pool A/B classification rules may be updated by HKEX; please refer to HKEX official announcements for the latest information.
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