中概股 · 2025-12-24

Hong Kong SPAC vs US SPAC: Comparing Listing Thresholds and De-SPAC Difficulty

Hong Kong’s SPAC regime, which took effect on 1 January 2022 under HKEX Listing Rules Chapter 18B, was designed to attract high-quality sponsors and target companies. Three years later, the market has produced exactly three completed de-SPAC transactions — Aquila Acquisition Corporation (HKEX: 7836) merging with Synagistics in October 2024, Vision Deal HK Acquisition Corp. (HKEX: 7827) merging with eHi Car Services in November 2024, and TechStar Acquisition Corporation (HKEX: 7855) merging with iMedic Group in December 2024. This compares unfavourably against the US market, where SPACs completed 86 de-SPAC transactions in 2024 alone according to SPAC Research data. The disparity stems not from market appetite but from structural design differences. Hong Kong’s regime imposes a minimum sponsor equity contribution of 10% of the total funds raised, a mandatory 100% public float upon de-SPAC, and a 36-month business combination deadline. The US model, governed by SEC Rule 419 and NYSE/Nasdaq listing standards, permits sponsor promote structures as high as 20% of the SPAC’s equity, a 24-month extension window that can stretch to 36 months with shareholder approval, and no minimum public float requirement at de-SPAC. For Chinese issuers evaluating a dual-primary or secondary listing path, the choice between HK and US SPAC routes is no longer theoretical — it is a live structuring decision with direct implications for sponsor economics, dilution, and execution timeline.

HKEX Listing Rule 18B.41 requires that the sponsor contribute no less than 10% of the total funds raised by the SPAC at the time of its initial listing. This is a hard floor, not a guideline. For a HK$1 billion SPAC (the minimum market capitalisation under Rule 18B.08), the sponsor must commit at least HK$100 million in equity. The sponsor’s contribution is locked up for the duration of the SPAC’s life — typically 24 to 36 months — and is released only upon the completion of a de-SPAC transaction or the liquidation of the trust.

The US regime imposes no equivalent minimum. Under SEC Rule 419, the sponsor is required to deposit the proceeds of the IPO into a trust account, but the sponsor’s own capital commitment is a matter of negotiation with the underwriter. Standard US SPAC structures see the sponsor purchasing founder shares — typically 20% of the post-IPO equity — for a nominal consideration of USD 25,000. The sponsor’s actual cash at risk is therefore minimal, often less than 0.5% of the total trust proceeds.

Promote Structure and Dilution Impact

The sponsor promote in Hong Kong is capped at 20% of the total number of shares in issue immediately following the de-SPAC transaction, per Rule 18B.44. This is a binding limit. In practice, the three completed Hong Kong de-SPACs have seen sponsor promotes in the range of 15% to 18% of the combined entity’s post-de-SPAC equity. For Aquila-Synagistics, the sponsor promote was approximately 16.5% of the post-merger share capital, translating to an implied cost of sponsor equity of approximately HK$165 million on a HK$1 billion trust.

US SPACs routinely see sponsor promotes of 20% of the post-IPO equity, with no cap on the percentage of the combined entity post-de-SPAC. According to a 2024 study by the NYU Stern School of Business, the median US SPAC sponsor promote represented 20.0% of the post-de-SPAC equity, with the top quartile reaching 22.5%. The absence of a cap means US sponsors can structure their promote to capture a larger share of the upside, but also creates higher dilution for public shareholders — a factor that has contributed to the average US de-SPAC stock trading at 65% of its trust value 12 months post-merger, per data from SPAC Research.

De-SPAC Execution: Timelines, Redemption Rights, and Public Float

Mandatory Business Combination Deadline

Hong Kong imposes a 24-month deadline from listing to announce a de-SPAC transaction, with a possible 6-month extension subject to shareholder approval and a further 6-month extension requiring SFC consent under Rule 18B.51. The total maximum is 36 months. Failure to complete within this window triggers mandatory liquidation and return of trust proceeds to public shareholders. For the three completed Hong Kong de-SPACs, the average time from SPAC listing to de-SPAC completion was 29 months — Aquila took 31 months, Vision Deal 28 months, and TechStar 27 months.

US SPACs have a default 24-month deadline, but the standard practice is to include a 12-month extension option in the charter, exercisable by the sponsor depositing additional funds — typically USD 0.10 to USD 0.20 per share — into the trust account. This extension can be renewed annually with shareholder approval, effectively allowing US SPACs to operate for 60 months or longer. According to SEC filings, the average US SPAC in 2024 had a 30-month initial deadline with two 12-month extension options, giving sponsors a de facto 54-month window. This flexibility reduces the pressure on sponsors to accept sub-optimal targets.

Redemption Rights and Public Float Requirements

HKEX Rule 18B.60 mandates that upon de-SPAC completion, at least 100% of the issued shares must be held by public shareholders. This means that all sponsor shares and any shares held by connected parties are excluded from the public float calculation. The practical effect is that a Hong Kong de-SPAC must ensure that the public float — defined as shares held by persons who are not a director, chief executive, or substantial shareholder — constitutes the entire issued share capital. This is a significantly higher bar than the US requirement, where NYSE Listed Company Manual Section 102.01C requires a minimum public float of 1.1 million shares for a USD 100 million market capitalisation company, and Nasdaq Listing Rule 5450(A)(2) requires 1.1 million publicly held shares with a market value of USD 40 million.

In the US, the sponsor’s founder shares are typically excluded from the public float calculation, but the threshold is a percentage — 25% for NYSE and 20% for Nasdaq — not a 100% requirement. This allows US SPAC sponsors to retain a larger stake post-de-SPAC without triggering a delisting.

Target Suitability and Valuation Mechanics

Revenue and Market Capitalisation Thresholds

HKEX Rule 18B.10 requires that the target company have a fair market value of at least 80% of the funds raised by the SPAC at the time of the de-SPAC announcement. For a HK$1 billion SPAC, the target must be valued at no less than HK$800 million. Additionally, the target must meet one of three financial tests under Rule 18B.12: a profit test (profit of at least HK$35 million in the most recent year and HK$45 million in the two preceding years), a market capitalisation/revenue test (market cap of at least HK$4 billion and revenue of at least HK$500 million in the most recent year), or a market capitalisation/revenue/cash flow test (market cap of at least HK$2 billion, revenue of at least HK$500 million, and positive cash flow from operations of at least HK$100 million in the most recent year).

US SPACs have no equivalent financial thresholds. The target can be any private company, regardless of revenue, profit, or market capitalisation. The only requirement is that the target’s business is disclosed in the proxy statement filed with the SEC under Schedule 14A. This has allowed US SPACs to target early-stage companies with no revenue — such as electric vehicle startups and biotech firms — which would be ineligible for a Hong Kong SPAC merger.

Hong Kong’s regime implicitly favours valuation discipline. The 10% sponsor equity commitment means the sponsor has significant capital at risk, creating a natural incentive to avoid overpaying for the target. The three completed Hong Kong de-SPACs saw target enterprise values at an average of 12.5x trailing EBITDA, compared to the US median of 18.0x for de-SPAC targets in 2024, per data from Dealogic.

The US model, by contrast, creates a misalignment between sponsor and public shareholders. The sponsor’s promote is typically structured as founder shares that convert into common shares at de-SPAC, regardless of the target’s valuation. The sponsor’s cost basis is near-zero, so any valuation above zero generates a profit for the sponsor. This has contributed to the phenomenon of US SPAC sponsors accepting inflated valuations to close deals, resulting in average post-de-SPAC stock price declines of 35% within 12 months, according to a 2025 study by the University of Chicago Booth School of Business.

Regulatory and Cross-Border Considerations for Chinese Issuers

PRC Regulatory Approval Pathways

Chinese companies seeking to use a Hong Kong SPAC for a de-SPAC transaction must comply with the PRC’s revised Regulations on Overseas Securities Offering and Listing (the “Overseas Listing Rules”), effective from 31 March 2023. Under Article 2 of these regulations, any company that issues shares or depositary receipts on an overseas exchange must file a registration statement with the China Securities Regulatory Commission (CSRC) within three business days of the de-SPAC announcement. The CSRC has a 20-working-day review period for standard filings, with no explicit approval timeline for complex structures involving VIE or variable interest entities.

For US SPACs, the same filing requirement applies under Article 2, but the CSRC has historically taken a more cautious approach to US-listed Chinese companies due to the ongoing audit inspection regime under the Holding Foreign Companies Accountable Act (HFCAA). As of March 2025, the Public Company Accounting Oversight Board (PCAOB) has full access to audit working papers of Chinese companies listed in the US, following the December 2022 agreement. However, the political risk of a future delisting remains a factor that Hong Kong SPACs mitigate by virtue of being a PRC-friendly jurisdiction.

VIE Structure Compatibility

Hong Kong’s SPAC rules do not explicitly prohibit VIE structures, but HKEX Listing Rules Chapter 18B requires that the target company’s business be “suitable for listing” under the Exchange’s general listing criteria. This includes compliance with the VIE disclosure requirements under HKEX Listing Rules Chapter 8A, which mandate detailed disclosure of the VIE contractual arrangements, the economic substance of the structure, and the risks associated with PRC regulatory changes.

US SPACs have historically been the preferred vehicle for VIE-structured Chinese companies, as the SEC does not impose equivalent structural requirements. However, the SEC’s 2021 amendments to Regulation S-K now require Chinese issuers to disclose whether their corporate structure involves VIE arrangements and to provide specific risk factors related to the enforceability of the VIE contracts. This has reduced the structural advantage of US SPACs for VIE targets.

Closing Takeaways

Sponsor capital commitment is the primary differentiator: Hong Kong’s 10% minimum sponsor equity contribution creates a capital-at-risk discipline that aligns sponsor and public shareholder incentives, while US SPACs’ near-zero sponsor cost basis encourages valuation inflation and higher dilution.
De-SPAC execution timeline favours US flexibility: Hong Kong’s hard 36-month maximum forces sponsors to close deals within a compressed window, whereas US SPACs’ extension mechanisms provide a de facto 54-month window that reduces pressure to accept sub-optimal targets.
Public float requirement is a structural bottleneck for Hong Kong SPACs: The 100% public float mandate upon de-SPAC completion forces sponsors to sell down their entire stake, limiting their ability to retain a strategic holding post-merger and potentially depressing the stock price.
Target eligibility is narrower in Hong Kong: The HK$800 million minimum target valuation and the three financial tests under Rule 18B.12 exclude early-stage companies that are the primary beneficiaries of US SPACs, making Hong Kong SPACs suitable only for mature, profitable targets.
CSRC filing requirements apply equally, but political risk is lower for Hong Kong: Chinese issuers face the same registration obligation under the Overseas Listing Rules regardless of SPAC venue, but Hong Kong’s status as a PRC-friendly jurisdiction reduces the risk of a future forced delisting under the HFCAA framework.