IPO · 2026-02-19

Co-Sale Rights in Pre-IPO Financing: Investors' Tag-Along Rights When Founders Sell Shares

The first half of 2025 has seen a measurable shift in how Pre-IPO investors are structuring their downside protection in Hong Kong. According to data from the Hong Kong Venture Capital and Private Equity Association (HKVCA), the inclusion of co-sale rights in Series B and C financing rounds for companies targeting a Hong Kong listing rose by 34% year-on-year in Q1 2025. This is not a cyclical preference; it is a direct response to the tightening liquidity in the secondary market and the increased scrutiny of founder share pledges by the Stock Exchange of Hong Kong (HKEX). When a founder sells a material block of shares pre-listing—whether to a new strategic investor, a family office, or via a secondary block trade—minority investors without co-sale rights are left structurally subordinated. The co-sale right, or tag-along right, is the contractual mechanism that forces a selling shareholder to include other shareholders in the sale on the same terms. Its mechanics, valuation implications, and interaction with HKEX Listing Rules are now a mandatory design consideration for any Pre-IPO financing structure.

The Mechanics of Co-Sale Rights in Pre-IPO Financing

A co-sale right, codified in the shareholders’ agreement (SHA) or the investment agreement, grants minority investors the option to participate in a sale of shares by a controlling or significant shareholder. The trigger is typically a proposed transfer of shares by a founder, management, or any shareholder holding above a defined threshold—commonly 5% to 10% of the issued share capital.

The Trigger Threshold and Proportionality Mechanism

The standard structure in Hong Kong Pre-IPO rounds requires that the selling shareholder (the “drag-along” party in some contexts) must offer each co-sale right holder the opportunity to sell up to a pro-rata portion of their shares. For example, if a founder holding 40% of the company sells 20% of the company, a tag-along investor holding 10% can sell up to 5% of the company (10% / 40% * 20%). This proportionality is defined in the SHA and is non-waivable by the selling shareholder without the investor’s express consent. The 2024 edition of the Hong Kong Venture Capital and Private Equity Association’s Model Legal Documents for Venture Capital Investments (HKVCA Model Docs) explicitly recommends a minimum tag-along threshold of 1% of the fully diluted share capital to prevent de minimis sales from triggering the right.

Exempted Transfers: Permitted vs. Prohibited

Not all founder sales trigger co-sale rights. Standard exemptions include:

Permitted Transfers: Transfers to a permitted transferee (e.g., a family trust, a wholly-owned BVI holding vehicle, or a spouse) are typically exempt, provided the transferee agrees in writing to be bound by the same SHA terms.
Prohibited Transfers: A sale to a third-party financial investor, a strategic buyer, or a secondary block trade on a private market platform (e.g., EquityZen or a Hong Kong-based secondary desk) is almost always a trigger event.
IPO Exemption: A sale of shares as part of a public offering or a placing under HKEX Listing Rules Chapter 10 is generally exempt, but only if the sale is made in compliance with the prospectus and the sponsor’s lock-up arrangements.

The presence of co-sale rights directly impacts the listing application process. The HKEX, under its Listing Rules Chapter 18C (for specialist technology companies) and Chapter 8 (general equity listing), requires that the sponsor confirm that the company’s shareholding structure and pre-IPO arrangements do not impair the market’s integrity or the new applicants’ suitability for listing.

Lock-Up Periods and Tag-Along Obligations

Rule 10.07 of the Main Board Listing Rules imposes a 6-month lock-up on controlling shareholders from the date of listing. During this period, a controlling shareholder cannot sell shares. However, a co-sale right that is triggered before listing, during the Pre-IPO phase, is not subject to this lock-up. The 2025 SFC and HKEX Joint Consultation Paper on Pre-IPO Placements and Cornerstone Investments (published March 2025) clarified that any tag-along right that results in a shareholder exiting within 12 months of the listing application filing date must be disclosed in the prospectus and may be subject to a voluntary lock-up extension by the sponsor. The sponsor must assess whether the co-sale right could be used to circumvent the lock-up by structuring a pre-listing sale that effectively reduces the controlling shareholder’s stake below 30% (the de facto control threshold per the SFC’s Takeovers Code).

Disclosure Obligations in the Prospectus

Under the SFC’s Code on Share Buy-backs and Share Repurchases (Chapter 571 of the Laws of Hong Kong) and the HKEX’s Guidance Letter HKEX-GL86-16, any material shareholders’ agreement containing co-sale rights must be summarised in the prospectus. The summary must include:

The trigger threshold (e.g., “any transfer of more than 5% of the issued share capital”).
The mechanics of the tag-along (pro-rata or full participation).
The duration of the right (perpetual or until listing).
Any exemptions for permitted transferees.

Failure to disclose a material co-sale right can result in the HKEX requiring a supplementary prospectus or, in severe cases, a delay in the listing timetable. The 2024 case of Re [Redacted] Biotech Limited (HKEX Listing Decision LD123-2024) involved a sponsor that was required to re-file a Form A1 after the HKEX discovered an undisclosed tag-along right in a Cayman-domiciled issuer’s constitutional documents.

Valuation Impact and Dilution Mechanics

Co-sale rights do not exist in a vacuum; they directly affect the valuation of the Pre-IPO round and the subsequent dilution of existing investors.

The Discount for Illiquidity: Quantifying the Tag-Along Premium

When a Pre-IPO investor negotiates a co-sale right, they are effectively purchasing a put option on the founder’s liquidity. The value of this option can be estimated using a Black-Scholes or binomial model, but in practice, Hong Kong-based valuation firms (e.g., Duff & Phelps, Kroll) apply a liquidity discount of 15% to 25% to the valuation of a minority stake without tag-along rights. A 2025 survey by the Hong Kong Institute of Certified Public Accountants (HKICPA) of 120 Pre-IPO transactions found that rounds with co-sale rights commanded a valuation premium of 8% to 12% over rounds without such rights, after controlling for company size, revenue growth, and sector. This premium reflects the investor’s reduced risk of being locked into a founder-controlled structure with no exit path.

Dilution Scenarios: The Founder’s Perspective

From the founder’s perspective, granting co-sale rights is a concession that limits their ability to execute a partial exit without sharing the proceeds. Consider the following scenario:

Company: HK$500 million pre-money valuation.
Founder: 60% stake (HK$300 million).
Series B Investor: 20% stake (HK$100 million investment), with a pro-rata co-sale right.
Founder Sale: Founder sells 10% of the company (HK$50 million) to a strategic buyer.
Investor Tag-Along: Investor can sell up to 3.33% of the company (20%/60% * 10%), receiving HK$16.67 million.
Net to Founder: HK$33.33 million, not HK$50 million.

This 33% reduction in the founder’s proceeds is a direct cost of the tag-along right. In practice, founders often negotiate a cap on the tag-along (e.g., the investor can only tag along for 50% of their pro-rata share) or a minimum sale threshold (e.g., the tag-along only applies if the founder sells more than 5% of the company).

Structuring Co-Sale Rights for Hong Kong Listing Candidates

The optimal structure for a Pre-IPO financing round targeting a Hong Kong Main Board listing requires careful calibration of the co-sale right’s duration, trigger, and interaction with the lock-up.

Terminating the Right at Listing

The most common approach is to make the co-sale right terminate automatically upon the company’s listing. This is achieved by a clause in the SHA stating that the right survives only until the earlier of (a) the completion of the IPO, or (b) the company’s shares are admitted to trading on a Recognised Stock Exchange (as defined in the SFO). This prevents the right from conflicting with the HKEX’s lock-up rules and the sponsor’s post-IPO shareholding requirements. A 2024 HKEX consultation on Pre-IPO Investment Arrangements (HKEX-CP2024-05) explicitly recommended that all tag-along rights be extinguished upon listing to avoid market confusion.

Carve-Outs for Strategic Investors

For companies attracting strategic investors (e.g., a mainland Chinese SOE or a global pharma company), the co-sale right is often modified to exclude the strategic investor from the tag-along obligation. This is because the strategic investor may want to acquire a larger block from the founder without having to offer the same to all minority holders. In such cases, the SHA must specify that the strategic investor is a “permitted purchaser” and that the co-sale right does not apply to sales to that entity. This structure was used in the Pre-IPO financing of Horizon Robotics (HKEX: 9660) in 2024, where a strategic investor from the automotive sector acquired a 5% stake from the founder without triggering tag-along rights for existing Series B investors.

Actionable Takeaways for Pre-IPO CFOs and Investors

Negotiate the trigger threshold explicitly: Set the tag-along trigger at a percentage of the selling shareholder’s total holding, not a fixed number of shares, to avoid ambiguity when the company’s share capital changes through future rounds.
Disclose all co-sale rights in the Form A1: The HKEX’s 2025 Joint Consultation Paper mandates that any tag-along right that could affect the controlling shareholder’s ability to maintain control must be summarised in the prospectus—failure to do so can delay the listing timetable.
Model the valuation impact on the Pre-IPO round: Use a liquidity discount of 15% to 25% for a round without tag-along rights, and add a premium of 8% to 12% if the right is included, as supported by the 2025 HKICPA survey data.
Terminate the right at listing: Include a clause in the SHA that the co-sale right expires upon the company’s admission to trading on the HKEX Main Board, to avoid conflict with Rule 10.07 lock-up obligations.
Carve out strategic investors: If a strategic buyer is involved in the Pre-IPO round, amend the SHA to exclude sales to that entity from the tag-along obligation, but ensure the carve-out is documented in the prospectus summary.