Shareholding Concentration Analysis via CCASS: Top Custodians' Combined Stake

The SFC’s 2024-25 enforcement priorities, coupled with the HKEX’s October 2024 amendments to the Listing Rules on connected transactions and the ongoing market volatility in 2025, have sharpened the focus on shareholding transparency. For listed issuers, sponsors, and investors, the Central Clearing and Settlement System (CCASS) remains the only publicly accessible, near-real-time window into the ownership structure of Hong Kong-listed stocks. Yet, the raw CCASS data—which records positions held by 27 designated custodians—is often misinterpreted. A critical, under-utilised metric is the combined stake of the top 3 to 5 custodians, which can serve as a proxy for institutional versus retail concentration, flag potential cornered-market risks, and even signal the likelihood of a successful placing or a forced delisting. This analysis decodes how to calculate and interpret this combined stake, using specific 2025 examples and referencing the HKEX’s latest guidance on disclosure of interests (Part XV of the Securities and Futures Ordinance, Cap. 571). The methodology is not about identifying individual beneficial owners but about measuring the structural risk embedded in the custodian profile.

The Mechanics of the Top Custodian Combined Stake Metric

Defining the Dataset: The 27 CCASS Custodians

The CCASS database, operated by HKSCC, lists positions held by 27 approved custodians (as of Q1 2025). These include global giants like Citibank, HSBC, JPMorgan Chase, Bank of China (Hong Kong), Standard Chartered, and Morgan Stanley. Each custodian’s position represents the aggregate holdings of its underlying clients—which can range from a single sovereign wealth fund to thousands of retail margin accounts. The combined stake of the top 3 or top 5 custodians is calculated by summing their respective percentages of total shares in issue (excluding treasury shares, as defined under the Listing Rules). For example, if HSBC holds 28%, Citibank 15%, and JPMorgan 8%, the top 3 combined stake is 51%. This figure is a proxy for the degree of institutional intermediation and, conversely, the fragmentation of the register.

The Calculation: From Raw Data to Actionable Signal

The raw data is sourced from the CCASS Daily Movement Summary, published on the HKEX website. The calculation is straightforward: (Sum of shares held by top 3 custodians) / (Total shares in issue) × 100. The total shares in issue figure must be taken from the most recent monthly return (Form F-1) filed with the Registrar of Companies. A critical adjustment: the calculation must exclude shares held by the issuer in treasury (per LR 10.06) and any shares held by the issuer’s own nominee company, which is often a separate entity. For example, in the case of a Main Board issuer with 1 billion shares in issue, if HSBC holds 280 million, Citibank 150 million, and BOCI 80 million, the top 3 combined stake is 51%. A combined stake above 70% suggests extreme concentration; below 20% implies a highly fragmented retail-dominated register.

Interpreting the Thresholds: What the Numbers Mean

A top 3 combined stake above 70% is a clear red flag. It indicates that a very small number of intermediaries control the vast majority of the float. This structure is common in newly listed companies post-IPO, where cornerstone investors and placing agents hold large blocks through a single custodian. In 2025, the SFC’s 2024-25 Annual Report highlighted that it had issued 12 restriction notices under Section 285 of the SFO in cases where a single custodian’s position accounted for over 60% of the stock’s CCASS holdings, suggesting potential cornered-market manipulation. Conversely, a top 3 combined stake below 20% is typical of large-cap blue chips with deep liquidity, such as HSBC Holdings (0005.HK), where the top 3 custodians (HSBC, Citibank, JPMorgan) collectively hold around 18-22%. For mid-cap stocks (market cap HKD 5-50 billion), a reading between 40% and 60% is the norm. A reading above 80% in a mid-cap stock warrants immediate due diligence, as it may indicate a single sponsor or a tight group of placing agents controlling the register.

Practical Applications for IPO and Secondary Market Analysis

Pre-IPO and IPO Pricing Signals

For sponsors structuring an IPO, the CCASS top custodian combined stake of comparable companies in the same sector provides a benchmark for expected institutional demand. If the top 3 combined stake of a comparable Main Board IPO (e.g., a 2024 biotech listing) was 65%, a new biotech issuer targeting a similar profile would need to ensure its cornerstone investor group can replicate that level of concentration to signal institutional confidence. Conversely, a top 3 combined stake below 30% for a newly listed stock suggests that the placing was heavily retail-oriented, which can lead to higher post-listing volatility. In 2024, the HKEX’s Listing Committee (Guidance Letter GL94-19) explicitly noted that a low institutional concentration post-IPO could trigger a review of the sponsor’s placing conduct under LR 3A.02. The metric also helps analysts gauge the likelihood of a successful top-up placing or a block trade. A high combined stake (e.g., 75%) means that the top custodians’ clients are the only realistic buyers for a large secondary block, making pricing negotiations more predictable.

Identifying Cornered-Market and Price Manipulation Risks

The SFC’s enforcement division has increasingly used CCASS custodian concentration as a screening tool. In a 2025 enforcement case involving a GEM-listed company (case reference: SFC v. [Redacted], 2025), the regulator noted that the top 2 custodians held 82% of the free float, which facilitated a circular trading scheme. The combined stake metric is a leading indicator: a sudden, unexplained increase in the top 3 combined stake over a 30-day period (e.g., from 40% to 65%) without a corresponding announcement of a major share acquisition (under Part XV of the SFO) is a strong signal of potential market manipulation. For IBD analysts, this metric is a critical input for the sponsor’s internal risk assessment under the SFC’s Code of Conduct for Persons Licensed by or Registered with the SFC (paragraph 17.1). A stock with a top 3 combined stake above 80% and low trading volume (e.g., average daily turnover below HKD 5 million) is a high-risk candidate for a suspension or an SFC investigation.

Post-Listing Liquidity and Free Float Analysis

The HKEX’s minimum free float requirement (25% for Main Board, 25% for GEM under Listing Rule 8.08) is measured by shares not held by the issuer’s directors, substantial shareholders, or connected persons. However, the CCASS top custodian combined stake offers a complementary measure: it reveals how that free float is distributed. If the top 3 custodians hold 90% of the free float, the stock is effectively illiquid for retail investors, as the majority of shares are locked in institutional custody. This is often the case for family-controlled companies where the family’s shares are held through a single custodian (e.g., HSBC). For example, in the case of a 2024 Main Board listing of a Chinese real estate developer, the family’s 65% stake was held entirely through HSBC, while the remaining 35% free float was split across 5 other custodians. The top 3 combined stake of the free float (excluding the family’s custodian) was 28%, indicating a relatively fragmented register. This metric is critical for market makers and liquidity providers (LPs) who need to assess the cost of providing two-way quotes. A concentrated free float (top 3 combined > 70%) means that LP inventory must be sourced from a small number of counterparties, increasing bid-ask spreads.

Regulatory and Compliance Implications

Part XV of the SFO and the 5% Disclosure Threshold

The SFO requires any person holding 5% or more of the voting shares of a listed company to file a disclosure of interest (DI) notice. However, the CCASS top custodian combined stake can reveal situations where multiple parties, each holding below 5%, are aggregated through a single custodian. For example, if a custodian holds 12% of a stock, but that 12% is composed of 30 different clients each holding below 0.5%, no individual DI notice is triggered. The SFC’s 2024-25 Annual Report acknowledged this gap and stated it is reviewing the threshold for “indirect interests” under Section 316 of the SFO. For compliance officers, a top 3 combined stake above 70% should trigger a review of whether any of the underlying clients are acting in concert (per the SFC’s Takeovers Code, Rule 3). Failure to identify a concert party group can lead to a breach of the mandatory general offer obligation under the Takeovers Code.

The 2024 Amendments to the Listing Rules on Connected Transactions

The HKEX’s October 2024 amendments to the Listing Rules on connected transactions (effective 1 January 2025) introduced a new requirement for issuers to disclose the identities of all “connected persons” holding shares through a custodian. This directly impacts the interpretation of the CCASS top custodian combined stake. If a connected person (e.g., a director or a substantial shareholder) holds shares through one of the top 3 custodians, the issuer must now disclose that holding in the annual report. For example, if the CEO’s 15% stake is held through Citibank, the issuer must state this in the “Interests of Directors” section of the annual report. This change means that the top custodian combined stake is no longer a purely anonymous metric; it now carries a disclosure obligation for the issuer. Analysts should cross-reference the top custodian positions with the issuer’s annual report to identify any undisclosed connected holdings.

The SFC’s 2025 Enforcement Focus on Custodian Concentration

In a 2025 circular to all licensed corporations, the SFC emphasised that it will scrutinise any custodian account where the aggregate position exceeds 30% of the issuer’s total shares in issue, particularly if the issuer has a market capitalisation below HKD 1 billion. The circular (SFC/LC/2025/01) specifically references the top custodian combined stake as a “key indicator” for potential market misconduct. For sponsors and compliance officers, this means that any IPO or secondary placing where the top 3 custodian combined stake is projected to exceed 70% must be flagged in the sponsor’s internal risk assessment. The SFC has also indicated it will request underlying client data from custodians in such cases, under Section 185 of the SFO. This regulatory focus makes the top custodian combined stake a mandatory data point for any due diligence report prepared for a listing application or a material transaction.

Actionable Takeaways for Market Participants

• For sponsors and underwriters: Calculate the top 3 custodian combined stake of the target issuer’s sector peers as a benchmark for the IPO placing structure; a reading above 70% in a mid-cap stock should trigger a review of the placement agent concentration under LR 3A.02.
• For IBD analysts and family offices: Use a 30-day rolling average of the top 3 combined stake as a screening tool for potential SFC investigations; a sudden increase of 20 percentage points without a corresponding DI filing is a red flag.
• For compliance officers: Cross-reference the top 3 custodian positions with the issuer’s annual report to identify any undisclosed connected person holdings under the 2024 Listing Rule amendments.
• For market makers and liquidity providers: A top 3 combined free-float stake above 70% implies a high cost of sourcing inventory and a wider bid-ask spread; adjust pricing models accordingly.
• For retail investors: A top 3 combined stake above 80% in a stock with a market cap below HKD 2 billion indicates a high risk of cornered-market manipulation; avoid direct investment without a clear understanding of the underlying custodian clients.