X0202 SCHEDULE 13D/A 0001633120 XXXXXXXX LIVE 6 Ordinary Shares, nominal value Euro 0.04 per share 06/26/2026 false 0001612940 N71542109 ProQR Therapeutics N.V.

Zernikedreef 9 Leiden P7 2333 CK

Van Herk Investments B.V. 31-10-241-1555 Lichtenauerlaan 30, The Netherlands P7 3062 ME Evan S. Simpson 44 20 795984-26 1 New Fetter Lane, London X0 EC4A 1AN 0001633120 N Van Herk Investments B.V. BK WC PF N P7 15384250.00 0.00 15384250.00 0.00 15384250.00 N 10.9 CO * Based on 141,119,032 ordinary shares, nominal value Euro 0.04 per share, of ProQR Therapeutics N.V. (the "Issuer") expected to be issued and outstanding as of June 26, 2026, as described in the Issuer's Prospectus Supplement dated June 25, 2026 and filed with the SEC pursuant to Rule 424(b)(5) on June 26, 2026 (the "Prospectus Supplement") (after giving effect to the issuances of shares contemplated therein, which the Prospectus Supplement stated were expected to be completed on June 26, 2026). Y Van Herk Investments THI B.V. BK WC PF N P7 0.00 15384250.00 0.00 15384250.00 15384250.00 N 10.9 CO * Based on 141,119,032 ordinary shares, nominal value Euro 0.04 per share, of the Issuer expected to be issued and outstanding as of June 26, 2026, as described in the Prospectus Supplement (after giving effect to the issuances of shares contemplated therein, which the Prospectus Supplement stated were expected to be completed on June 26, 2026). Y Van Herk Private Equity Investments B.V. BK WC PF N P7 0.00 15384250.00 0.00 15384250.00 15384250.00 N 10.9 CO * Based on 141,119,032 ordinary shares, nominal value Euro 0.04 per share, of the Issuer expected to be issued and outstanding as of June 26, 2026, as described in the Prospectus Supplement (after giving effect to the issuances of shares contemplated therein, which the Prospectus Supplement stated were expected to be completed on June 26, 2026). Y Stichting Administratiekantoor Penulata BK WC PF N P7 0.00 15384250.00 0.00 15384250.00 15384250.00 N 10.9 OO * Based on 141,119,032 ordinary shares, nominal value Euro 0.04 per share, of the Issuer expected to be issued and outstanding as of June 26, 2026, as described in the Prospectus Supplement (after giving effect to the issuances of shares contemplated therein, which the Prospectus Supplement stated were expected to be completed on June 26, 2026). Y Van Herk Management Services B.V. BK WC PF N P7 0.00 15384250.00 0.00 15384250.00 15384250.00 N 10.9 CO * Based on 141,119,032 ordinary shares, nominal value Euro 0.04 per share, of the Issuer expected to be issued and outstanding as of June 26, 2026, as described in the Prospectus Supplement (after giving effect to the issuances of shares contemplated therein, which the Prospectus Supplement stated were expected to be completed on June 26, 2026). Y Onroerend Goed Beheer- en Beleggingsmaatschappij A. van Herk B.V. BK WC PF N P7 0.00 15384250.00 0.00 15384250.00 15384250.00 N 10.9 CO * Based on 141,119,032 ordinary shares, nominal value Euro 0.04 per share, of the Issuer expected to be issued and outstanding as of June 26, 2026, as described in the Prospectus Supplement (after giving effect to the issuances of shares contemplated therein, which the Prospectus Supplement stated were expected to be completed on June 26, 2026). Y A. van Herk Holding B.V. BK WC PF N P7 0.00 15384250.00 0.00 15384250.00 15384250.00 N 10.9 CO * Based on 141,119,032 ordinary shares, nominal value Euro 0.04 per share, of the Issuer expected to be issued and outstanding as of June 26, 2026, as described in the Prospectus Supplement (after giving effect to the issuances of shares contemplated therein, which the Prospectus Supplement stated were expected to be completed on June 26, 2026). Y Stichting Administratiekantoor Abchrys BK WC PF N P7 0.00 15384250.00 0.00 15384250.00 15384250.00 N 10.9 OO * Based on 141,119,032 ordinary shares, nominal value Euro 0.04 per share, of the Issuer expected to be issued and outstanding as of June 26, 2026, as described in the Prospectus Supplement (after giving effect to the issuances of shares contemplated therein, which the Prospectus Supplement stated were expected to be completed on June 26, 2026). Y Adrianus van Herk BK WC PF N P7 0.00 15384250.00 0.00 15384250.00 15384250.00 N 10.9 IN * Based on 141,119,032 ordinary shares, nominal value Euro 0.04 per share, of the Issuer expected to be issued and outstanding as of June 26, 2026, as described in the Prospectus Supplement (after giving effect to the issuances of shares contemplated therein, which the Prospectus Supplement stated were expected to be completed on June 26, 2026). Ordinary Shares, nominal value Euro 0.04 per share ProQR Therapeutics N.V. Zernikedreef 9 Leiden P7 2333 CK This Schedule 13D/A (this "Amendment No. 6") amends the Schedule 13D filed on May 28, 2025, as amended by Amendment No. 1 filed on August 20, 2025, Amendment No. 2 filed on September 4, 2025, Amendment No. 3 filed on September 30, 2025, Amendment No. 4 filed on February 6, 2026 and Amendment No. 5 filed on June 3, 2026 (collectively, the "Original Schedule 13D," and as amended and supplemented by this Amendment No. 6, the "Schedule 13D"). Items 1, 2, and 5 of the Original Schedule 13D are hereby amended and supplemented to the extent hereinafter expressly set forth in this Amendment No. 6. Except as amended hereby, the original disclosure set forth in the Original Schedule 13D shall remain unchanged. All capitalized terms used and not expressly defined herein have the respective meanings ascribed to such terms in the Original Schedule 13D. The information previously provided in response to Item 2 is hereby amended and restated by replacing the text thereof in its entirety with the following: This statement is being filed by (i) Van Herk Investments B.V., a private company with limited liability incorporated under the laws of the Netherlands ("VHI"), with respect to Ordinary Shares, nominal value Euro 0.04 per share (the "Ordinary Shares"), beneficially owned by it, (ii) Van Herk Investments THI B.V., a private company with limited liability incorporated under the laws of the Netherlands ("VHIT"), with respect to Ordinary Shares beneficially owned by VHI, (iii) Van Herk Private Equity Investments B.V., a private company with limited liability incorporated under the laws of the Netherlands ("VHPI"), with respect to Ordinary Shares beneficially owned by VHI and VHIT, (iv) Stichting Administratiekantoor Penulata, a foundation organized under the laws of the Netherlands ("Penulata"), with respect to Ordinary Shares beneficially owned by VHI, VHIT and VHPI, (v) Van Herk Management Services B.V., a private company with limited liability incorporated under the laws of the Netherlands ("VHMS"), with respect to Ordinary Shares beneficially owned by VHI, VHIT and VHPI, (vi) Onroerend Goed Beheer- en Beleggingsmaatschappij A. van Herk B.V., a private company with limited liability incorporated under the laws of the Netherlands ("OGBBA"), with respect to Ordinary Shares beneficially owned by VHI, VHIT, VHPI and VHMS, (vii) A. van Herk Holding B.V., a private company with limited liability incorporated under the laws of the Netherlands ("Holdings"), with respect to Ordinary Shares beneficially owned by VHI, VHIT, VHPI, VHMS and OGBBA, (viii) Stichting Administratiekantoor Abchrys, a foundation organized under the laws of the Netherlands ("Abchrys"), with respect to Ordinary Shares beneficially owned by VHI, VHIT, VHPI, VHMS, OGBBA and Holdings, and (ix) Adrianus van Herk ("Mr. van Herk") with respect to Ordinary Shares beneficially owned by VHI, VHIT, VHPI, VHMS, OGBBA, Holdings, Penulata and Abchrys. Each of Mr. van Herk, VHIT, VHPI, Penulata, VHMS, OGBBA, Holdings and Abchrys disclaims beneficial ownership of the securities covered by this statement. The principal business address of each of Mr. van Herk, VHI, VHIT, VHPI, Penulata, VHMS, OGBBA, Holdings and Abchrys is: Lichtenauerlaan 30 3062 ME Rotterdam The Netherlands Mr. van Herk is (i) an investor, (ii) the holder of all of the depositary receipts issued by Penulata and Abchrys, (iii) the sole board member of Penulata and Abchrys, and (iv) the sole managing director of VHMS, OGBBA and Holdings. Penulata holds substantially all of the issued and outstanding shares of VHPI. VHPI is the sole shareholder of VHIT. VHIT is the sole shareholder of VHI. VHI is principally engaged in making investments. Abchrys holds substantially all of the issued and outstanding shares of Holdings. Holdings is the sole shareholder of OGBBA. OGBBA is the sole shareholder of VHMS and is principally engaged in making investments. VHMS is the sole managing director of VHI, VHIT and VHPI. During the last five years, none of the Reporting Persons, nor, to the knowledge of the Reporting Persons, any of the executive officers or directors of the Reporting Persons, if applicable, has been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors). During the last five years, none of the Reporting Persons, nor, to the knowledge of the Reporting Persons, any of the executive officers or directors of the Reporting Persons, if applicable, has been a party to a civil proceeding of a judicial or administrative body of a competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws. Each of VHI, VHIT, VHPI, VHMS, OGBBA and Holdings is a private company with limited liability incorporated under the laws of the Netherlands. Penulata and Abchrys are Netherlands foundations. Mr. van Herk is a citizen of the Netherlands. The information previously provided in response to Item 5 is hereby amended and restated by replacing the text thereof in its entirety with the following: The information set forth in or incorporated by reference in Items 2, 3, 4 and 6 and on the cover pages of this Schedule 13D is incorporated by reference in its entirety into this Item 5. The Reporting Persons hold an aggregate 15,384,250 ordinary shares, nominal value Euro 0.04 per share, of the Issuer, representing approximately 10.9% of the ordinary shares outstanding as of June 26, 2026. All such ownership percentages of the securities reported herein are based on 141,119,032 ordinary shares, nominal value Euro 0.04 per share, of the Issuer expected to be issued and outstanding as of June 26, 2026, as described in the Prospectus Supplement (after giving effect to the issuances of shares contemplated therein, which the Prospectus Supplement stated were expected to be completed on June 26, 2026). This Amendment No. 6 is being filed to reflect a change in the percentage previously reported solely as a result of the change in the outstanding ordinary shares as a result of the issuances of shares contemplated in the Prospectus Supplement. Except for the change in percentage ownership described herein, there have been no other material changes to the information previously reported since the filing of Amendment No. 5. The information set forth in or incorporated by reference in Items 2, 3, 4 and 6 and on the cover pages of this Schedule 13D is incorporated by reference in its entirety into this Item 5. Except as set forth in this Schedule 13D, no transactions in Ordinary Shares of the Issuer have been effected during the past sixty days by any of the Reporting Persons. Except as set forth herein, to the knowledge of the Reporting Persons, no other person has the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, any securities of the Issuer beneficially owned by the Reporting Persons as described in this Item 5. Not applicable. Van Herk Investments B.V. /s/ Erik G.A. Esveld 06/30/2026 Van Herk Investments THI B.V. /s/ Erik G.A. Esveld 06/30/2026 Van Herk Private Equity Investments B.V. /s/ Erik G.A. Esveld 06/30/2026 Stichting Administratiekantoor Penulata /s/ Erik G.A. Esveld 06/30/2026 Van Herk Management Services B.V. /s/ Erik G.A. Esveld 06/30/2026 Onroerend Goed Beheer- en Beleggingsmaatschappij A. van Herk B.V. /s/ Erik G.A. Esveld 06/30/2026 A. van Herk Holding B.V. /s/ Erik G.A. Esveld 06/30/2026 Stichting Administratiekantoor Abchrys /s/ Erik G.A. Esveld 06/30/2026 Adrianus van Herk /s/ Erik G.A. Esveld 06/30/2026 * Pursuant to a Power of Attorney, dated as of September 16, 2019, by and among the Reporting Persons.