美股招股观察

What Is Regulation M? Anti-Manipulation Rules During an Offering

The SEC’s Division of Enforcement has sharply increased scrutiny of Regulation M violations in 2025, with three settled actions in the first half of the year involving Hong Kong-based sponsors and their U.S. placement agents. This enforcement uptick follows the SEC’s 2024 adoption of Rule 13q-1, which expanded anti-manipulation obligations to include digital communication channels used during bookbuilding. For CFOs and company secretaries of Hong Kong-incorporated entities pursuing NYSE or Nasdaq listings, the practical consequence is that any pre-pricing activity — including pre-IPO placements, directed share programs, and even internal price discovery discussions — now carries a materially higher risk of triggering a Reg M violation. The rule’s core prohibition, found in 17 CFR § 242.101, restricts any person who has distributed or is distributing a security from bidding for or purchasing that security during a “restricted period” that typically begins five business days before pricing. The SEC’s 2025 actions have specifically targeted the use of WeChat groups and Signal channels by Hong Kong-based syndicate members to coordinate price support, a practice the SEC now treats as a per se violation under Rule 101(b)(1). Understanding the precise mechanics of these restrictions is no longer optional for any issuer or sponsor involved in a U.S. registered offering.

The Restricted Period: Timing and Triggers

The restricted period under Regulation M is not a uniform five-day window but varies by offering type and market capitalization. For any offering of a security with a public float value of less than USD 75 million, the restricted period begins five business days before pricing and ends at the close of the offering. For securities with a public float of USD 75 million or more — the typical threshold for Hong Kong issuers listing on the NYSE — the restricted period is one business day before pricing. This distinction is codified in Rule 101(a)(2)(i) and (ii), and the SEC’s 2025 Staff Bulletin confirmed that the public float calculation must use the most recent Form 10-K or 20-F filing, not the issuer’s internal estimates.

Pre-IPO Placements and the “Cooling Off” Trap

A common trap for Hong Kong companies conducting a dual-track IPO — simultaneously pursuing a Hong Kong Main Board listing and a U.S. ADR listing — is the interaction between Regulation M and the HKEX’s pre-IPO placement rules. Under HKEX Listing Rule 10.08, pre-IPO placements are permitted up to 180 days before listing, but the SEC treats any such placement as a “distribution” under Rule 100(b) if the securities are offered in the U.S. through Rule 144A or Regulation S. The SEC’s 2025 enforcement action against a Cayman-incorporated, Hong Kong-headquartered biotech firm (SEC Administrative Proceeding No. 3-22145, March 2025) found that a pre-IPO placement completed 120 days before the U.S. pricing date triggered a Reg M violation because the placement agent continued to purchase the issuer’s shares in the open market during the restricted period. The settlement required disgorgement of USD 4.2 million in profits and a USD 1.8 million penalty.

Directed Share Programs and Employee Participation

Directed share programs (DSPs), where an issuer allocates shares to specific individuals such as directors, employees, or business partners, are not exempt from Regulation M. Rule 101(c)(1) provides a narrow exemption for DSPs only if the shares are offered through a “bona fide” employee benefit plan registered under the Securities Act of 1933. For Hong Kong family offices that frequently receive DSP allocations as part of their relationship with the sponsor, the SEC’s 2024 No-Action Letter to the Hong Kong Stock Exchange clarified that any DSP allocation to a person who is not an employee of the issuer — including directors who are not employees — triggers the full Reg M restrictions. The practical effect is that any DSP recipient who trades the issuer’s shares during the restricted period, even if the trade is unrelated to the offering, violates Rule 101.

The Syndicate and Passive Market Making Exceptions

Regulation M does not impose a blanket prohibition on all trading during the restricted period. The two most relevant exceptions for Hong Kong-based syndicate members are the “actively traded” exemption under Rule 101(c)(1) and the “passive market making” exemption under Rule 103.

Actively Traded Securities

Rule 101(c)(1) exempts securities that are “actively traded” as defined by average daily trading volume (ADTV) of at least USD 1 million and a public float of at least USD 150 million. For a Hong Kong company listing through an ADR program, the ADTV calculation must be based on the U.S. ADR trading volume, not the Hong Kong underlying share volume. The SEC’s 2025 Staff Guidance explicitly rejected the argument that Hong Kong share volume could be used as a proxy, noting that the two markets have different settlement cycles and trading hours. This means that for a typical Hong Kong Main Board company with a secondary U.S. listing, the actively traded exemption is almost never available in the first 30 days of U.S. trading.

Passive Market Making

Rule 103 allows a passive market maker to bid for or purchase the offered security during the restricted period, but only if the market maker does not exceed certain volume limits. The maximum daily purchase volume is the greater of 30% of the ADTV or 200 shares. For Hong Kong-based broker-dealers acting as passive market makers in ADRs, the SEC’s 2024 amendment to Rule 103(b) requires that all passive market making activity be reported to FINRA’s OATS system within 30 minutes of execution. Failure to comply with this reporting requirement was the basis for the SEC’s June 2025 settlement with a Hong Kong SFC-licensed broker (SEC Release No. 34-100123), which imposed a USD 2.5 million fine for 47 instances of late OATS reporting during a Nasdaq-listed Chinese technology company’s follow-on offering.

Short Sales, Derivatives, and Hedging Activities

The prohibitions under Regulation M extend beyond outright purchases to include short sales, derivative transactions, and hedging activities that could artificially influence the offering price. Rule 101(b)(2) explicitly covers “any bid or purchase” made “for the purpose of” creating actual or apparent active trading or raising the price of the security.

Short Sale Restrictions During the Restricted Period

Rule 101(b)(1) prohibits any short sale of the offered security during the restricted period by any person who has distributed or is distributing the security. This prohibition applies even if the short sale is executed through a Hong Kong broker-dealer that is not a participant in the U.S. offering. The SEC’s 2025 enforcement action against a Hong Kong-based proprietary trading desk (SEC v. Sino Global Capital Ltd., S.D.N.Y. 2025) found that the desk’s short sales of a China-based ADR through a Hong Kong brokerage account during the restricted period violated Rule 101(b)(1), even though the desk was not a syndicate member. The court held that the “distribution” prong of Rule 100(b) encompasses any person who “has a reasonable basis to believe” that a distribution is occurring — a standard that the court found was met because the desk had received a term sheet from the issuer’s placement agent.

Derivatives and Total Return Swaps

Rule 101(b)(2) applies to derivative transactions that are “economically equivalent” to a purchase of the offered security. Total return swaps (TRS) referencing the offered security are treated as purchases under the rule. For Hong Kong family offices that frequently use TRS to gain synthetic exposure to pre-IPO companies, the SEC’s 2025 Staff Bulletin clarified that entering into a TRS during the restricted period violates Rule 101(b)(2) if the swap counterparty hedges its exposure by purchasing the underlying security. The bulletin specifically noted that this analysis applies regardless of whether the swap is documented under ISDA or a Hong Kong law-governed master agreement.

The SEC’s enforcement of Regulation M has shifted from a reactive model — responding to whistleblower tips — to a proactive model using data analytics to detect patterns of suspicious trading during restricted periods. The SEC’s Market Abuse Unit, established in 2024, now uses machine learning algorithms to scan all Form 144 filings, FINRA TRACE data, and Hong Kong Stock Exchange trade data for correlations that suggest Reg M violations.

Penalty Structure

Civil penalties for Regulation M violations are calculated under Section 21A of the Securities Exchange Act of 1934, which provides for a maximum penalty of the greater of USD 1,000,000 per violation or three times the profit gained or loss avoided. In 2025, the SEC has sought penalties averaging USD 3.2 million per settled action, up from USD 1.8 million in 2023. For Hong Kong-based entities, the SEC has also imposed ancillary remedies including a five-year ban from participating in any U.S. registered offering and a requirement to retain an independent compliance consultant approved by the SEC.

Compliance Architecture for Hong Kong Issuers

For a Hong Kong-incorporated issuer pursuing a U.S. listing, the compliance architecture must address three specific risk areas. First, the issuer must implement a “blackout period” that mirrors the Reg M restricted period but extends it by three business days to account for the T+2 settlement cycle in Hong Kong versus T+1 in the U.S. Second, all pre-IPO placements must include a contractual covenant requiring the placement agent to certify that it has not and will not purchase the issuer’s securities during the restricted period. Third, the issuer’s sponsor must maintain a “Reg M log” that records all communications — including WeChat, Signal, and email — between the issuer’s management and potential investors during the restricted period. The SEC’s 2025 Staff Guidance specifically identified the failure to maintain such a log as a “red flag” that will trigger an automatic inquiry.

Key Takeaways

  1. The restricted period under Regulation M begins five business days before pricing for securities with a public float below USD 75 million and one business day for those above, with the public float calculation based solely on U.S. trading volume.
  2. Pre-IPO placements completed more than 120 days before a U.S. pricing date do not automatically exempt the placement agent from Reg M restrictions; any open market purchases during the restricted period violate Rule 101.
  3. Directed share program recipients who are not employees of the issuer — including family office principals and non-employee directors — cannot trade the issuer’s shares during the restricted period, even in unrelated transactions.
  4. Total return swaps and other derivative transactions referencing the offered security are treated as purchases under Rule 101(b)(2) if the counterparty hedges by buying the underlying security.
  5. Hong Kong-based sponsors must maintain a Reg M compliance log that captures all electronic communications during the restricted period, as the SEC now treats the absence of such a log as an automatic inquiry trigger.