[Form 4] TScan Therapeutics, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Dropbox, Inc. (ticker: DBX) filed a Form 4 on 2 July 2025 reporting two open-market sales of Class A common stock by Chief Financial Officer Timothy Regan.

• Transaction dates & volumes: 2,500 shares sold on 30 Jun 2025 at $28.40; 10,000 shares sold on 1 Jul 2025 at a weighted-average $27.9392.
• Total shares sold: 12,500, representing approximately 2.4 % of the executive’s post-sale holdings.
• Remaining ownership: 516,094 Class A shares held directly.
• Trading plan: All sales executed under a Rule 10b5-1 plan adopted on 15 May 2024, indicating pre-arranged, schedule-based transactions.
• Equity mix: Remaining position includes restricted stock awards/units that vest through 15 Feb 2029; any unvested awards cancel if employment ends.

The filing discloses no derivative transactions and contains no indication of additional insider participation. While insider sales can be perceived negatively, the modest size relative to Regan’s continuing stake and the existence of a 10b5-1 plan mitigate potential signaling risk. No operational or financial performance metrics were provided in this document.

Positive

• Rule 10b5-1 plan in place reduces chance of opportunistic trading and signals adherence to compliance best practices.
• CFO retains a large 516,094-share stake, maintaining alignment with shareholder interests.

Negative

• Insider sale by CFO can be interpreted as reduced confidence, even if modest.
• No offsetting insider purchases or operational disclosures provided to counter potential negative sentiment.

Insights

Sell-Side Equity Analyst

TL;DR: CFO’s 12.5k share sale (~$0.35 m) is small relative to >500k holdings; neutral signal given pre-arranged 10b5-1 plan.

From a valuation perspective, this disposition equates to roughly two trading days of average DBX volume and only ~2 % of the executive’s stake, limiting informational content. The continuing 516 k share position plus multi-year RSU vesting indicates sustained alignment with shareholders. I view the transaction as routine portfolio diversification, not a thesis-altering event.

Corporate Governance Specialist

TL;DR: Insider sale by a key officer is modest but still a mildly negative governance datapoint.

Even with 10b5-1 protection, market participants often discount insider selling by C-suite executives. The filing offers transparency on plan adoption and weighted-average pricing, but lacks detail on motive or future intent. Given insider trading research linking sequential sales to underperformance, I assign a slight negative governance bias, though magnitude is limited by the executive’s residual ownership.

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^*

BAKER BROS. ADVISORS LP

(Last) (First) (Middle)

860 WASHINGTON STREET, 3RD FLOOR

(Street)

NEW YORK NY 10014

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
TScan Therapeutics, Inc. [ TCRX ]

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

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

3. Date of Earliest Transaction (Month/Day/Year)
06/30/2025

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

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

	Form filed by One Reporting Person
X	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

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
Non- Qualified Stock Option (right to buy)	$1.45	06/30/2025		A		67,000(1)		(1)	06/29/2035	Common Stock	67,000	$0	67,000	I	See Footnotes(2)(3)(4)(5)(6)(7)(8)
Non- Qualified Stock Option (right to buy)	$1.45	06/30/2025		A		67,000(1)		(1)	06/29/2035	Common Stock	67,000	$0	67,000	I	See Footnotes(2)(4)(5)(6)(7)(8)(9)

1. Name and Address of Reporting Person^*

BAKER BROS. ADVISORS LP

(Last) (First) (Middle)

860 WASHINGTON STREET, 3RD FLOOR

(Street)

NEW YORK NY 10014

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

667, L.P.

(Last) (First) (Middle)

860 WASHINGTON STREET, 3RD FLOOR

(Street)

NEW YORK NY 10014

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

Baker Bros. Advisors (GP) LLC

(Last) (First) (Middle)

860 WASHINGTON STREET, 3RD FLOOR

(Street)

NEW YORK NY 10014

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

Baker Brothers Life Sciences LP

(Last) (First) (Middle)

860 WASHINGTON STREET, 3RD FLOOR

(Street)

NEW YORK NY 10014

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

BAKER FELIX

(Last) (First) (Middle)

860 WASHINGTON STREET, 3RD FLOOR

(Street)

NEW YORK NY 10014

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

BAKER JULIAN

(Last) (First) (Middle)

860 WASHINGTON STREET, 3RD FLOOR

(Street)

NEW YORK NY 10014

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

Explanation of Responses:

1. Includes 67,000 non-qualified stock options ("Stock Options") exercisable solely into common stock ("Common Stock") of TScan Therapeutics, Inc. (the "Issuer") granted by the Issuer to Dr. Stephen R. Biggar, a full-time employee of Baker Bros. Advisors LP (the "Adviser"), on June 30, 2025, in his capacity as a director of the Issuer, pursuant to the Issuer's Amended and Restated 2021 Equity Incentive Plan (the "Incentive Plan"). The Stock Options have a strike price of $1.45 per share, and vest on the earlier of the first anniversary of the grant date or the date of the next annual meeting of stockholders of the Issuer, subject to Dr. Biggar's continued service on the board of directors of the Issuer (the "Board") through the vesting date. The Stock Options expire on June 29, 2035.

2. Dr. Biggar serves on the Board as a representative of 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds") and their affiliates and control persons.

3. After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Biotech Capital, L.P. and (ii) 667, Julian C. Baker and Felix J. Baker each may be deemed to have an indirect pecuniary interest in the Stock Options reported in column 9 of Table II held for the benefit of 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP), LLC, due to their interest in 667 and Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667.

4. The Adviser serves as the investment adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held for the benefit of the Funds. Baker Bros. Advisors (GP) LLC ("the Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held for the benefit of the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held for the benefit of the Funds.

5. Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held for the benefit of the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

6. Pursuant to the policies of the Adviser, Dr. Biggar does not have a right to any of the Issuer's securities issued as compensation for his service on the Board and the Funds are entitled to an indirect proportionate pecuniary interest in such securities. The Funds each own an indirect proportionate pecuniary interest in such securities. Solely as a result of their ownership interest in (i) the general partners of the Funds and (ii) the Funds, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the shares of Common Stock, Stock Options and Common Stock issued upon exercise of Stock Options (i.e. no direct pecuniary interest) issued as compensation for such Board service.

7. Pursuant to the policies of the Adviser, the Adviser has voting and dispositive power over the Stock Options and any Common Stock received as a result of the exercise of Stock Options.

8. The acquisition of Stock Options reported on this form represents a single grant to Dr. Biggar of 67,000 Stock Options on Table II. This grant of 67,000 Stock Options for Dr. Biggar is reported for each of the Funds as each has an indirect pecuniary interest in such securities.

9. After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Brothers Life Sciences Capital, L.P. and (ii) Life Sciences, Julian C. Baker and Felix J. Baker each may be deemed to have an indirect pecuniary interest in the Stock Options reported in column 9 of Table II held for the benefit of Life Sciences, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP), LLC, due to their interest in Life Sciences and Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences.

Remarks:

Dr. Stephen R. Biggar, a full-time employee of Baker Bros. Advisors LP, is a director of TScan Therapeutics, Inc. (the "Issuer"). By virtue of their representation on the board of directors of the Issuer, for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, the reporting persons are deemed directors by deputization of the Issuer.

	By: Baker Bros. Advisors LP, Name: Scott L. Lessing, Title: President /s/ Scott L. Lessing	07/02/2025
	Baker Bros. Advisors LP, Mgmt. Co. and Inv. Adviser to 667, L.P., pursuant to authority granted by Baker Biotech Capital, L.P., GP to 667, L.P. Name: Scott L. Lessing, Title: President /s/ Scott L. Lessing	07/02/2025
	/s/ Julian C. Baker	07/02/2025
	/s/ Felix J. Baker	07/02/2025
	By: Baker Bros. Advisors (GP) LLC, Name: Scott L. Lessing, Title: President /s/ Scott L. Lessing	07/02/2025
	Baker Bros. Advisors LP, Mgmt. Co. and Inv. Adviser to BAKER BROTHERS LIFE SCIENCES, L.P., pursuant to authority granted by Baker Brothers Life Sciences Capital, L.P., GP to Baker Brothers Life Sciences, L.P., Name: Scott L. Lessing, Title: President /s/	07/02/2025
	** Signature of Reporting Person	Date
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FAQ

How many Dropbox (DBX) shares did the CFO sell?

12,500 Class A shares were sold across two days: 2,500 on 06/30/25 and 10,000 on 07/01/25.

What was the average sale price of the DBX shares?

Shares were sold at $28.40 and a weighted-average $27.9392, respectively.

Does the CFO still hold Dropbox stock after the sale?

Yes. 516,094 shares of Class A common stock remain in his direct ownership.

Was the sale conducted under a trading plan?

Yes, both transactions were executed under a Rule 10b5-1 plan adopted on 15 May 2024.

Did the filing disclose any derivative transactions?

No. Table II shows no derivative activity; only open-market sales of common stock were reported.

What happens to the CFO’s unvested RSUs if he leaves Dropbox?

Any unvested restricted stock awards/units will be cancelled upon termination of service.