X0202 SCHEDULE 13D/A 0000310051 XXXXXXXX LIVE 30 Common Stock, $1.00 par value 03/14/2026 false 0000703604 520776105 Distribution Solutions Group, Inc.

301 Commerce Street Suite 1700 Fort Worth TX 76102

Jacob D. Smith 817-332-3235 301 Commerce Street, Suite 1600 Fort Worth TX 76102 0001406372 N LKCM Private Discipline Master Fund, SPC / PDLP Lawson, LLC b WC N TX 3578228 0 3578228 0 3578228 N 7.7 OO 0001406371 N LKCM Investment Partnership, L.P. b WC N TX 552500 0 552500 0 552500 N 1.2 PN 0001502285 N LKCM Micro-Cap Partnership, L.P. b WC N DE 56470 0 56470 0 56470 N 0.1 PN 0001502283 N LKCM Core Discipline, L.P. b WC N DE 23182 0 23182 0 23182 N 0.1 PN 0001621801 N LKCM Headwater Investments II, L.P. b WC N DE 1184652 0 1184652 0 1184652 N 2.6 PN 0001713995 N LKCM Headwater II Sidecar Partnership, L.P. b WC N DE 0 0 0 0 0 N 0 PN 0001764096 N LKCM Headwater Investments III, L.P. b WC N DE 0 0 0 0 0 N 0 PN 0001921598 N 301 HW Opus Investors, LLC b WC N DE 16000000 0 16000000 0 16000000 N 34.6 OO 0001921624 N LKCM TE Investors, LLC b WC N DE 8000000 0 8000000 0 8000000 N 17.3 OO 0001765653 N Headwater Lawson Investors, LLC b WC N DE 3522988 0 3522988 0 3522988 N 7.6 OO 0001955947 N LKCM Headwater Investments IV, L.P. b WC N DE 3434044 0 3434044 0 3434044 N 7.4 PN 0000310051 N Luther King Capital Management Corporation b N DE 36357588 0 36357588 0 36357588 N 78.7 IA CO 0001290407 N J. Luther King, Jr. b N X1 36357588 0 36357588 0 36357588 N 78.7 IN 0001406297 N J. Bryan King b PF N X1 35838638 0 35838638 0 35838638 N 77.6 IN Common Stock, $1.00 par value Distribution Solutions Group, Inc. 301 Commerce Street Suite 1700 Fort Worth TX 76102 This Amendment No. 30 to Schedule 13D amends and supplements the Schedule 13D filed by the Reporting Persons with respect to the Common Stock, par value $1.00 per share ("Common Stock"), of Distribution Solutions Group, Inc. (the "Issuer"). Except as set forth below, all previous Items remain unchanged. Capitalized terms used herein but not defined herein shall have the meanings given to them in the Schedule 13D, as amended, filed with the Securities and Exchange Commission. Each of the Reporting Persons hereby expressly disclaims membership in a "group" under the Securities Exchange Act of 1934, as amended, with respect to the securities reported herein, and this Schedule 13D shall not be deemed to be an admission that any such Reporting Person is a member of such a group. Each of the Reporting Persons hereby expressly disclaims beneficial ownership of the securities reported herein, other than to the extent of its pecuniary interest therein, and this Schedule 13D shall not be deemed to be an admission that any such Reporting Person is the beneficial owner of the securities reported herein for purposes of the Securities Exchange Act of 1934, as amended, or for any other purpose. On March 14, 2026, LKCM Headwater Investments, LLC, on behalf of its affiliates and related parties, submitted a proposal to the Board of Directors of the Issuer regarding a preliminary, non-binding proposal to acquire all of the outstanding shares of Common Stock of the Issuer not currently owned by LKCM Headwater Investments, LLC and its affiliates and related parties (the "Proposal"). A copy of the letter submitted by LKCM Headwater Investments, LLC to the Board of Directors of the Issuer is attached hereto as Exhibit 1 and incorporated by reference herein. The Reporting Persons expect to engage in discussions and other efforts with one or more shareholders, officers or directors of the Issuer, including their representatives or advisors or other third parties, regarding the Proposal and the potential transactions contemplated therein that, if effected, would likely result in, among other things, one or more of the matters identified in Items 4(a)-(j) of Schedule 13D. The Reporting Persons reserve their right, based on all relevant factors and subject to applicable law, at any time and from time to time, all without prior notice to the Issuer or otherwise, to take further action with respect to the Proposal or otherwise review or reconsider their position or take other action (including actions that could involve one or more of the types of transactions or have one or more of the results described in Items 4(a)-(j) of Schedule 13D) or formulate and implement any other plans or proposals with respect to any of the foregoing. As of March 14, 2026, the Reporting Persons may be deemed to beneficially own 36,357,588 shares of Common Stock (which represents approximately 78.7% of the outstanding Common Stock based upon information obtained from the Issuer's Form 10-K for the year ended December 31, 2025. PDP has sole voting and dispositive power over 3,578,228 shares of Common Stock. LIP has sole voting and dispositive power over 552,500 shares of Common Stock. HW2 has sole voting and dispositive power over 1,184,652 shares of Common Stock. Sidecar does not have voting and dispositive power over any shares of Common Stock. HWLI has sole voting and dispositive power over 3,522,988 shares of Common Stock. HW3 does not have voting or dispositive power over any shares of Common Stock. HW4 has sole voting and dispositive power over 3,434,044 shares of Common Stock. Gexpro Investors has sole voting and dispositive power over 16,000,000 shares of Common Stock. TestEquity Investors has sole voting and dispositive power over 8,000,000 shares of Common Stock. Micro has sole voting and dispositive power over 56,470 shares of Common Stock. Core has sole voting and dispositive power over 23,182 shares of Common Stock. LKCM has sole voting and dispositive power over 36,357,588 shares of Common Stock. J. Luther King, Jr. has sole voting and dispositive power over 36,357,588 shares of Common Stock. J. Bryan King has sole voting and dispositive power over 35,838,638 shares of Common Stock. Not applicable. Not applicable. Not appliable. Exhibit 1 - Letter from LKCM Headwater Investments, LLC, dated March 14, 2026, to the Board of Directors of the Issuer. LKCM Private Discipline Master Fund, SPC / PDLP Lawson, LLC /s/ J. Bryan King 03/16/2026 LKCM Investment Partnership, L.P. /s/ J Luther King, Jr. 03/16/2026 LKCM Micro-Cap Partnership, L.P. /s/ J. Bryan King 03/16/2026 LKCM Core Discipline, L.P. /s/ J. Bryan King 03/16/2026 LKCM Headwater Investments II, L.P. /s/ J. Bryan King 03/16/2026 LKCM Headwater II Sidecar Partnership, L.P. /s/ J. Bryan King 03/16/2026 LKCM Headwater Investments III, L.P. /s/ J. Bryan King 03/16/2026 301 HW Opus Investors, LLC /s/ J. Bryan King 03/16/2026 LKCM TE Investors, LLC /s/ J. Bryan King 03/16/2026 Headwater Lawson Investors, LLC /s/ J. Bryan King 03/16/2026 LKCM Headwater Investments IV, L.P. /s/ J. Bryan King 03/16/2026 Luther King Capital Management Corporation /s/ J. Bryan King 03/16/2026 J. Luther King, Jr. /s/ J. Luther King, Jr. 03/16/2026 J. Bryan King /s/ J. Bryan King 03/16/2026