How are Zai Lab (ZLAB) ADSs related to ordinary shares in this Form 4?

Each American Depositary Share represents ten ordinary shares of Zai Lab. The filing reports all figures in terms of ADSs, which are fully fungible with the underlying ordinary shares according to the disclosure.

Zai Lab (ZLAB) CEO Du Ying exercises 261,092 ADS options with tax shares

Filing Impact

(Neutral)

Filing Sentiment

(Neutral)

Form Type

Rhea-AI Filing Summary

Zai Lab Ltd Chairperson & CEO Du Ying reported routine equity compensation activity involving American Depositary Shares (ADSs). On May 19, Du Ying exercised stock options to acquire 261,092 ADSs at an exercise price of $1.74 per ADS and simultaneously used 117,435 ADSs, valued at $18.75 per ADS, to satisfy tax obligations through a tax-withholding disposition. Following these transactions, Du Ying directly held 1,266,283 ADSs. Each ADS represents ten ordinary shares of Zai Lab, and the activity was carried out under a pre-arranged Rule 10b5-1 trading plan. The filing shows an exercise-and-hold pattern with part of the shares applied to taxes and no open-market sale.

Insider Trade Summary 10b5-1

261,092 shares exercised/converted

Mixed 3 txns

Insider Du Ying

Role Chairperson & CEO

Type	Security	Shares	Price	Value
Exercise	Stock Options (Right to Buy)	261,092	$0.00	--
Exercise	American Depositary Shares	261,092	$1.74	$454K
Tax Withholding	American Depositary Shares	117,435	$18.75	$2.20M

Holdings After Transaction: Stock Options (Right to Buy) — 0 shares (Direct, null); American Depositary Shares — 1,383,718 shares (Direct, null)

Footnotes (1)

Each American Depositary Share ("ADS") represents ten Ordinary Shares of the issuer. Our ADSs and Ordinary Shares are fully fungible. For purposes of this Form 4, we are reporting this in terms of ADSs. The transactions reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on November 11, 2025. The option vested in equal annual installments over five years beginning on August 25, 2017, the first anniversary of the date of grant.

Key Figures

Options exercised: 261,092 ADSs at $1.74 Tax-withholding shares: 117,435 ADSs at $18.75 Direct holdings after transaction: 1,266,283 ADSs +2 more

5 metrics

Options exercised 261,092 ADSs at $1.74 Stock option exercise on May 19, 2026

Tax-withholding shares 117,435 ADSs at $18.75 Shares delivered to satisfy tax liability

Direct holdings after transaction 1,266,283 ADSs Direct ownership following May 19, 2026 transactions

ADS-to-ordinary ratio 1 ADS = 10 ordinary shares Equivalence disclosed for reporting purposes

Exercised option expiry August 25, 2026 Expiration date of exercised stock options

Key Terms

American Depositary Shares, Rule 10b5-1 trading plan, tax-withholding disposition, derivative security, +1 more

5 terms

American Depositary Shares financial

"Each American Depositary Share ("ADS") represents ten Ordinary Shares of the issuer."

American depositary shares (ADSs) are a way for investors in the United States to buy shares of foreign companies without dealing with international markets directly. They represent ownership in a foreign company's stock and are traded on U.S. stock exchanges, making it easier for American investors to buy, sell, and own parts of companies from around the world.

Rule 10b5-1 trading plan regulatory

"The transactions reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person."

A Rule 10b5-1 trading plan is a pre-arranged schedule that allows company insiders to buy or sell stock at specific times, even if they have inside information. It helps prevent accusations of unfair trading by making these transactions look planned and transparent, rather than sneaky or illegal.

tax-withholding disposition financial

"Payment of exercise price or tax liability by delivering securities"

A tax-withholding disposition is an event or transaction—such as selling or transferring securities, exercising options, or receiving compensation—that triggers a requirement to hold back part of the payment and remit it to tax authorities. It matters to investors because it reduces the cash they receive immediately and can change the timing and amount of taxable income, like a cashier taking a portion of your sale proceeds to pay taxes before you get the rest.

derivative security financial

"Exercise or conversion of derivative security"

A derivative security is a financial contract whose value comes from the price or performance of something else, such as a stock, bond, commodity, or market index. For investors it acts like an insurance policy or a wager: it can be used to protect against losses, lock in prices, or amplify gains and losses, so it can change a portfolio’s risk and potential return without owning the underlying asset directly.

Stock Options (Right to Buy) financial

"Stock Options (Right to Buy) ... the option vested in equal annual installments over five years"

Form 4 Insider Transactions: What Each Field Means →

05/21/2026 - 04:19 PM

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Du Ying

(Last)

(First)

(Middle)

C/O ZAI LAB LIMITED

314 MAIN STREET, 4TH FLOOR, SUITE 100

(Street)

CAMBRIDGE

MASSACHUSETTS

02142

(City)

(State)

(Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Zai Lab Ltd [ ZLAB ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director	10% Owner
X	Officer (give title below)	Other (specify below)
	Chairperson & CEO

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
05/19/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
American Depositary Shares⁽¹⁾	05/19/2026		M⁽²⁾		261,092	A	$1.74	1,383,718	D
American Depositary Shares⁽¹⁾	05/19/2026		F⁽²⁾		117,435	D	$18.75	1,266,283	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
Stock Options (Right to Buy)	$1.74	05/19/2026		M⁽²⁾			261,092	⁽³⁾	08/25/2026	American Depositary Shares⁽¹⁾	261,092	$0	0	D

Explanation of Responses:

1. Each American Depositary Share ("ADS") represents ten Ordinary Shares of the issuer. Our ADSs and Ordinary Shares are fully fungible. For purposes of this Form 4, we are reporting this in terms of ADSs.

2. The transactions reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on November 11, 2025.

3. The option vested in equal annual installments over five years beginning on August 25, 2017, the first anniversary of the date of grant.

	/s/ Bruce Blefeld, Attorney-in-Fact	05/21/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)

Source: View Original Filing on SEC EDGAR

FAQ

What insider transactions did Zai Lab (ZLAB) CEO Du Ying report?

Du Ying exercised stock options for 261,092 ADSs and used 117,435 ADSs to cover taxes. The remaining ADSs increased her direct stake, with no open-market sale disclosed in this filing.

How many Zai Lab (ZLAB) ADSs does Du Ying hold after this Form 4?

After the reported transactions, Du Ying directly holds 1,266,283 American Depositary Shares. This reflects option exercises and tax withholding, giving a clearer view of her updated equity position in Zai Lab.

Was there an open-market sale in Du Ying’s Zai Lab (ZLAB) Form 4?

No open-market sale was reported. Shares were disposed of only through tax withholding, where 117,435 ADSs were delivered to satisfy tax liabilities rather than being sold in the market.

At what price did Du Ying exercise Zai Lab (ZLAB) stock options?

She exercised stock options covering 261,092 ADSs at an exercise price of $1.74 per ADS. These options were previously granted and had vested over time before being exercised on May 19.

What does the Rule 10b5-1 plan note mean in Zai Lab (ZLAB) CEO’s Form 4?

The Form 4 states the transactions occurred under a Rule 10b5-1 trading plan adopted on November 11, 2025. Such plans pre-schedule trades, indicating the timing was set in advance rather than decided opportunistically.