Quanterix (QTRX) CFO adds stock as RSUs vest and shares withheld

Rhea-AI Filing Summary

Quanterix Corp Chief Financial Officer Vandana Sriram reported routine equity compensation activity involving restricted stock units. On June 15, 2026, restricted stock units converted into 1,833 shares of common stock, and 548 shares were withheld at $3.10 per share to cover tax obligations.

These transactions reflect RSU vesting and related tax-withholding dispositions, not open-market trades. Following the transactions, Sriram directly owns 30,261 shares of Quanterix common stock. Footnotes state RSUs convert one-for-one into common stock and describe multi-year vesting schedules for prior RSU grants.

Insider Trade Summary

1,833 shares exercised/converted

Mixed 9 txns

Insider Sriram Vandana

Role Chief Financial Officer

Type	Security	Shares	Price	Value
Exercise	Restricted Stock Unit	263	$0.00	--
Exercise	Restricted Stock Unit	514	$0.00	--
Exercise	Restricted Stock Unit	1,056	$0.00	--
Exercise	Common Stock	263	$0.00	--
Tax Withholding	Common Stock	79	$3.10	$244.90
Exercise	Common Stock	514	$0.00	--
Tax Withholding	Common Stock	154	$3.10	$477.40
Exercise	Common Stock	1,056	$0.00	--
Tax Withholding	Common Stock	315	$3.10	$976.50

Holdings After Transaction: Restricted Stock Unit — 3,682 shares (Direct, null); Common Stock — 30,261 shares (Direct, null)

Footnotes (1)

1. Restricted stock units convert into common stock on a one-for-one basis. On August 21, 2023, the reporting person was granted 12,624 restricted stock units, vesting 25% on the first anniversary of the grant date, with the remaining 75% vesting in 36 equal monthly installments on the 15th day of each month thereafter. On February 2, 2024, the reporting person was granted 24,675 restricted stock units, vesting 25% on the first anniversary of the grant date, with the remaining 75% vesting in 36 equal monthly installments on the 15th day of each month thereafter. On February 4, 2025, the reporting person was granted 50,712 restricted stock units, vesting 25% on the first anniversary of the grant date, with the remaining 75% vesting in 36 equal monthly installments on the 15th day of each month thereafter.

Key Figures

RSU conversions: 1,833 shares Shares withheld for taxes: 548 shares Post-transaction holdings: 30,261 shares +4 more

7 metrics

RSU conversions 1,833 shares Common stock from RSUs converting on June 15, 2026

Shares withheld for taxes 548 shares Tax-withholding dispositions at $3.10 per share

Post-transaction holdings 30,261 shares Quanterix common stock directly owned after transactions

Tax withholding price $3.10 per share Price used for F-code tax-withholding dispositions

2023 RSU grant 12,624 units Granted August 21, 2023 with 25% first-year vesting

2024 RSU grant 24,675 units Granted February 2, 2024 with staged monthly vesting

2025 RSU grant 50,712 units Granted February 4, 2025 with 25% cliff then monthly vesting

Key Terms

Restricted stock units, tax-withholding disposition, Exercise or conversion of derivative security, Form 4, +1 more

5 terms

Restricted stock units financial

"Restricted stock units convert into common stock on a one-for-one basis."

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

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.

Exercise or conversion of derivative security financial

"Exercise or conversion of derivative security."

Form 4 regulatory

"INSIDER FILING DATA (Form 4):"

Form 4 is a official document that company insiders, such as executives or major shareholders, file with regulators whenever they buy or sell company shares. It provides transparency about how those with inside knowledge are trading, helping investors see if insiders are confident in the company's prospects or may be selling for personal reasons. This information can influence investor decisions by revealing insiders' perspectives on the company's value.

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.

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Form 4 Insider Transactions: What Each Field Means →

Available on EDGAR 06/23/2026 - 05:06 PM Accepted by SEC EDGAR 06/23/2026 - 05:06 PM Learn about SEC filing dates

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

X

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^*

Sriram Vandana

(Last) (First) (Middle)

C/O QUANTERIX CORPORATION

900 MIDDLESEX TURNPIKE

(Street)

BILLERICA MASSACHUSETTS 01821

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Quanterix Corp [ QTRX ]

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

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Financial Officer

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
06/15/2026

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)
			Code	V	Amount	(A) or (D)	Price
Common Stock	06/15/2026		M		263	A	(1)	30,261	D
Common Stock	06/15/2026		F		79	D	$3.1	30,182	D
Common Stock	06/15/2026		M		514	A	(1)	30,696	D
Common Stock	06/15/2026		F		154	D	$3.1	30,542	D
Common Stock	06/15/2026		M		1,056	A	(1)	31,598	D
Common Stock	06/15/2026		F		315	D	$3.1	31,283	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)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Restricted Stock Unit	$0.00	06/15/2026		M			263	(2)	(2)	Common Stock	263	$0.00	3,682	D
Restricted Stock Unit	$0.00	06/15/2026		M			514	(3)	(3)	Common Stock	514	$0.00	10,283	D
Restricted Stock Unit	$0.00	06/15/2026		M			1,056	(4)	(4)	Common Stock	1,056	$0.00	33,810	D

Explanation of Responses:

1. Restricted stock units convert into common stock on a one-for-one basis.

2. On August 21, 2023, the reporting person was granted 12,624 restricted stock units, vesting 25% on the first anniversary of the grant date, with the remaining 75% vesting in 36 equal monthly installments on the 15th day of each month thereafter.

3. On February 2, 2024, the reporting person was granted 24,675 restricted stock units, vesting 25% on the first anniversary of the grant date, with the remaining 75% vesting in 36 equal monthly installments on the 15th day of each month thereafter.

4. On February 4, 2025, the reporting person was granted 50,712 restricted stock units, vesting 25% on the first anniversary of the grant date, with the remaining 75% vesting in 36 equal monthly installments on the 15th day of each month thereafter.

Remarks:

	/s/ Meghan Shevlin, Attorney-in-Fact	06/23/2026
	** 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)

FAQ

What did Quanterix (QTRX) CFO Vandana Sriram report in this Form 4?

Quanterix CFO Vandana Sriram reported routine equity compensation activity. Restricted stock units vested and converted into common shares, and some shares were withheld to satisfy tax obligations, with no open-market purchases or sales disclosed in these transactions.

How many Quanterix (QTRX) shares did the CFO receive from RSU vesting?

The CFO received 1,833 shares of Quanterix common stock from restricted stock units converting on June 15, 2026. These shares arose from previously granted RSUs that vest over time according to schedules described in the footnotes to the filing.

How many Quanterix (QTRX) shares were withheld for taxes in this filing?

A total of 548 shares of Quanterix common stock were withheld at $3.10 per share to cover tax liabilities. These tax-withholding dispositions are coded with transaction type F and are not open-market sales by the CFO.

What are the CFO’s Quanterix (QTRX) holdings after these transactions?

After the reported transactions, CFO Vandana Sriram directly holds 30,261 shares of Quanterix common stock. This figure reflects the net position after RSU conversions and related share withholding for taxes on the transaction date.

How do Quanterix (QTRX) restricted stock units convert into common stock?

The footnotes state that Quanterix restricted stock units convert into common stock on a one-for-one basis. RSUs from grants in 2023, 2024, and 2025 vest 25% after one year, with the remaining 75% vesting in equal monthly installments thereafter.

Were the Quanterix (QTRX) CFO’s transactions open-market buys or sells?

No open-market buys or sells are shown. The filing reflects RSU conversions coded M and tax-withholding dispositions coded F. These transactions arise from equity compensation and tax obligations rather than discretionary market trading decisions.