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).

1. Name and Address of Reporting Person* Mattoon Dawn (Last) (First) (Middle) C/O QUANTERIX CORPORATION, 900 MIDDLESEX TURNPIKE (Street) BILLERICA MA 01821 (City) (State) (Zip)	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) Sr. VP, Diagnostics
	3. Date of Earliest Transaction (Month/Day/Year) 06/21/2021
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) X Form filed by One Reporting Person Form filed by More than One Reporting Person

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	06/15/2021	06/21/2021(1)	S(2)		696	D	$64.3338	36,884	D
Common Stock	07/01/2021		M		9,806	A	$22.12	46,690(3)	D
Common Stock	07/01/2021		S(2)		5,093	D	$58.0732(4)	41,597(3)	D
Common Stock	07/01/2021		S(2)		3,361	D	$58.9102(5)	38,236(3)	D
Common Stock	07/02/2021		S(6)		168	D	$57.6396(7)	38,068(3)	D
Common Stock	07/02/2021		S(6)		52	D	$58.3881(8)	38,016(3)	D
Common Stock	07/02/2021		S(6)		127	D	$59.3432(9)	37,889(3)	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
Stock Option (right to buy)	$22.12	07/01/2021		M			9,806	(10)	02/23/2028	Common Stock	9,806	$0.00	22,070	D

Explanation of Responses:

1. The reporting person was not informed of this transaction until June 30, 2021. However, under SEC rules, the deemed execution date is the third trading day following the date of the transaction.

2. The sale of shares was effected pursuant to a Rule 10b5-1 trading plan adopted on March 15, 2021.

3. Includes 16,966 restricted stock units.

4. This transaction was executed in multiple trades at prices ranging from $57.57 to $58.52. The price reported reflects the weighted average sale price. The reporting person undertakes to provide upon request to the SEC staff, the issuer or any security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

5. This transaction was executed in multiple trades at prices ranging from $58.64 to $59.27. The price reported reflects the weighted average sale price. The reporting person undertakes to provide upon request to the SEC staff, the issuer or any security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

6. The sales of shares reported on this Form 4 were made solely to cover tax obligations upon the vesting of 750 RSUs.

7. This transaction was executed in multiple trades at prices ranging from $57.13 to $58.11. The price reported reflects the weighted average sale price. The reporting person undertakes to provide upon request to the SEC staff, the issuer or any security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

8. This transaction was executed in multiple trades at prices ranging from $58.17 to $59.03. The price reported reflects the weighted average sale price. The reporting person undertakes to provide upon request to the SEC staff, the issuer or any security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

9. This transaction was executed in multiple trades at prices ranging from $59.17 to $59.51. The price reported reflects the weighted average sale price. The reporting person undertakes to provide upon request to the SEC staff, the issuer or any security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

10. The option vests as to 25% of the shares on February 23, 2019 and vests as to an additional 2.083% of the shares per month for 36 months thereafter.

Remarks:

	/s/ Brian Keane, as Attorney-in-Fact	07/06/2021
	** 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).
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