John D. Duke - 16 Mar 2026 Form 4 Insider Report for HARVARD BIOSCIENCE INC (HBIO)

Role: Chief Executive Officer, Director
Signature: /s/ John D Duke
Issuer symbol: HBIO
Transactions as of: 16 Mar 2026
Net transactions value: $0
Form type: 4
Filing time: 17 Mar 2026, 17:56:45 UTC
Previous filing: 11 Aug 2025
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
Duke John D	Chief Executive Officer, Director	C/O HARVARD BIOSCIENCE, INC., 84 OCTOBER HILL ROAD, HOLLISTON	/s/ John D Duke	17 Mar 2026	0002071593

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	HBIO	Common Stock	Purchase		+5,000	+5%	$5.01^*	105,000	16 Mar 2026	Direct	F1, F2

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	Includes (a) 5,000 shares of common stock purchased on March 16, 2026, (b) an award of 50,000 restricted stock units (RSUs) that will vest in three equal installments on August 8, 2026, 2027 and 2028, subject to the terms set forth in an award agreement between the Issuer and the Reporting Person and (c) an award of 50,000 RSUs with performance based vesting conditions. These RSUs will vest upon the achievement of a relative total shareholder return of the Issuer's common stock during the period from August 8, 2025 to the earlier of (i) July 30, 2028, and (ii) the date of a change of control, measured relative to the Russell2000 index, subject to the terms set forth in an award agreement between the Issuer and the Reporting Person. The target number of these RSUs that may be earned is reported above; the maximum amount is 150% of the number reported.
F2	On March 13, 2026, the common stock of Harvard Bioscience, Inc. underwent a reverse stock split in a ratio of 10-for-1. The 50,000 restricted stock units referenced in Footnote 1(b) were previously reported as covering 500,000 restricted stock units and the 50,000 restricted stock units referenced in Footnote 1(c) were previously reported as covering 500,000 restricted stock units. These numbers have been adjusted to reflect the stock split that occurred on March 13, 2026.

Content

Includes (a) 5,000 shares of common stock purchased on March 16, 2026, (b) an award of 50,000 restricted stock units (RSUs) that will vest in three equal installments on August 8, 2026, 2027 and 2028, subject to the terms set forth in an award agreement between the Issuer and the Reporting Person and (c) an award of 50,000 RSUs with performance based vesting conditions. These RSUs will vest upon the achievement of a relative total shareholder return of the Issuer's common stock during the period from August 8, 2025 to the earlier of (i) July 30, 2028, and (ii) the date of a change of control, measured relative to the Russell2000 index, subject to the terms set forth in an award agreement between the Issuer and the Reporting Person. The target number of these RSUs that may be earned is reported above; the maximum amount is 150% of the number reported.

On March 13, 2026, the common stock of Harvard Bioscience, Inc. underwent a reverse stock split in a ratio of 10-for-1. The 50,000 restricted stock units referenced in Footnote 1(b) were previously reported as covering 500,000 restricted stock units and the 50,000 restricted stock units referenced in Footnote 1(c) were previously reported as covering 500,000 restricted stock units. These numbers have been adjusted to reflect the stock split that occurred on March 13, 2026.