Description of Securities

    As of March 1, 2022, Martin Midstream Partners L.P. has one class of securities registered under Section 12 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"): (1) our common units.

The following description of our common units is a summary and does not purport to be complete. It is subject to and qualified in its entirety by reference to our Third Amended and Restated Agreement of Limited Partnership, dated November 23, 2021 (our "Partnership Agreement"), which is incorporated by reference as an exhibit to the Annual Report on Form 10-K of which this Exhibit 4.3 is a part. We encourage you to read our Partnership Agreement for additional information.

    Our common units represent limited partner interests that entitle the holders to participate in our partnership distributions and to exercise the rights and privileges available to limited partners under our Partnership Agreement. References in this "Description of the Common Units" to "we," "us" and "our" mean Martin Midstream Partners L.P.

    As of March 1, 2022, we have 38,836,950 common units outstanding, 32,722,418 of which are held by the public, 4,203,823 are held by Martin Resource LLC, 889,444 are held by Cross Oil Refining & Marketing Inc. and 1,021,265 are held by Martin Product Sales LLC, each a wholly owned subsidiary of Martin Resource Management. The common units represent an aggregate 98.0% limited partner interest. Our general partner owns an aggregate 2.0% general partner interest in us.

    Our outstanding common units are traded on the Nasdaq National Market under the symbol "MMLP."

    The transfer agent and registrar for our common units is Computershare.

    Except as otherwise provided in the Partnership Agreement, the transfer of a common unit will not be recorded by the transfer agent or recognized by us unless the transferee executes and delivers a transfer application. By executing and delivering a transfer application, the transferee of common units:

•becomes the record holder of the common units and is an assignee until admitted into our partnership as a substituted limited partner;

•automatically requests admission as a substituted limited partner in our partnership;

•agrees to be bound by the terms and conditions of, and executes, our Partnership Agreement;

•represents that the transferee has the capacity, power and authority to enter into our Partnership Agreement;

•grants powers of attorney to officers of our general partner and any liquidator of us as specified in our Partnership Agreement; and

•makes the consents and waivers contained in our Partnership Agreement.

    An assignee will become a substituted limited partner of our partnership for the transferred common units upon the consent of our general partner and the recording of the name of the assignee on our books and records. Our general partner may withhold its consent in its sole discretion.

    A transferee’s broker, agent or nominee may complete, execute and deliver a transfer application. We are entitled to treat the record holder of a common unit as the absolute owner. In that case, the beneficial holder’s rights are limited solely to those that it has against the record holder as a result of any agreement between the beneficial owner and the record holder.

    Common units are securities and are transferable according to the laws governing transfer of securities. In addition to other rights acquired upon transfer, the transferor gives the transferee the right to request admission as a substituted limited partner in our partnership for the transferred common units. A purchaser or transferee of common units who does not execute and deliver a transfer application obtains only:

•the right to assign the common unit to a purchaser or other transferee; and

•the right to transfer the right to seek admission as a substituted limited partner in our partnership for the transferred common units.

Thus, a purchaser or transferee of common units who does not execute and deliver a transfer application:

•will not receive cash distributions, unless the common units are held in a nominee or "street name" account and the nominee or broker has executed and delivered a transfer application; and

•may not receive some U.S. federal income tax information or reports furnished to record holders of common units.

    Our Partnership Agreement requires that a transferor of common units provide the transferee with all information that may be necessary to transfer the common units. The transferor is not required to insure the execution of the transfer application by the transferee and has no liability or responsibility if the transferee neglects or chooses not to execute and forward the transfer application to the transfer agent.

    Until a common unit has been transferred on our books, we and the transfer agent may treat the record holder of the unit as the absolute owner for all purposes, except as otherwise required by law or applicable stock exchange regulations.

Our Partnership Agreement requires that, within 45 days after the end of each quarter, we distribute all of our available cash to unitholders of record on the applicable record date. Other than the requirement in our Partnership Agreement to distribute all of our available cash each quarter, we have no legal obligation to make quarterly cash distributions and the board of directors of our general partner has considerable discretion to determine the amount of our available cash each quarter. Available cash generally means, for each fiscal quarter, all cash and cash equivalents on hand at the end of each quarter less the amount of cash reserves our general partner determines in its reasonable discretion is necessary or appropriate to: (i) provide for the proper conduct of our business; (ii) comply with applicable law, any debt instruments or other agreements; or (iii) provide funds for distributions to unitholders and our general partner for any one or more of the next four quarters, plus all cash on the date of determination of available cash for the quarter resulting from working capital borrowings made after the end of the quarter. Working capital borrowings are borrowings that are made under our revolving credit facility or other arrangement requiring all borrowings thereunder to be reduced to a relatively small amount each year for an economically meaningful period of time and in all cases are used solely for working capital purposes or to pay distributions to partners.

If we dissolve in accordance with our Partnership Agreement, we will sell or otherwise dispose of our assets in a process called liquidation. We will first apply the proceeds of liquidation to the payment of our creditors. We will distribute any remaining proceeds to the holders of common units and our general partner, in accordance with their capital account balances, as adjusted to reflect any gain or loss upon the sale or other disposition of our assets in liquidation, all in accordance with the terms of our Partnership Agreement.

Except as described below regarding a person or group owning 20% or more of any class of units then outstanding, record holders of units on the record date will be entitled to notice of, and to vote at, meetings of our limited partners and to act upon matters for which approvals may be solicited.

Meetings of the unitholders may be called by our general partner or by unitholders owning at least 20% of the outstanding units of the class for which a meeting is proposed. The holders of a majority in voting power of the outstanding units of the class or classes for which a meeting has been called, represented in person or by proxy, will constitute a quorum unless any action by the unitholders requires approval by holders of a greater percentage of the units, in which case the quorum will be the greater percentage. For all matters presented to the limited partners at a meeting at which a quorum is present for which no minimum or other vote of the limited partners is specifically required pursuant to our Partnership Agreement, the rules and regulations of any national securities exchange on which the common units are admitted to trading, or applicable law

or pursuant to any regulation applicable to us or our partnership interests, a majority of the votes cast by the limited partners holding outstanding common units will be deemed to constitute the act of all limited partners (with abstentions and broker non-votes being deemed to not have been cast with respect to such matter). The general partner interest does not entitle our general partner to any vote other than its rights as general partner under our Partnership Agreement, will not be entitled to vote on any action required or permitted to be taken by the unitholders and will not count toward or be considered outstanding when calculating required votes, determining the presence of a quorum, or for similar purposes.

Each record holder of a unit has a vote according to its percentage interest in us. However, if at any time any person or group, other than our general partner and its affiliates, a direct transferee of our general partner and its affiliates, a transferee of such direct transferee, who is notified by our general partner that it will not lose its voting rights, or a person or a group who acquired 20% or more of any class of units issued by us with the prior approval of the board of directors of our general partner, acquires, in the aggregate, beneficial ownership of 20% or more of any class of units then outstanding, that person or group will lose voting rights on all of its units and the units may not be voted on any matter and will not be considered to be outstanding when sending notices of a meeting of unitholders, calculating required votes, determining the presence of a quorum, or for other similar purposes.

    The following matters require the unitholder vote specified below. Matters requiring the approval of a "unit majority" requires the approval of a majority of the outstanding common units.

Amendments to our Partnership Agreement may be proposed only by or with the consent of our general partner, which consent may be given or withheld in its sole discretion. In order to adopt a proposed amendment, other than the amendments discussed below, our general partner must seek written approval of the holders of the number of units required to approve the amendment or call a meeting of the limited partners to consider and vote upon the proposed amendment. Except as described below, an amendment must be approved by a unit majority.

Prohibited Amendments. No amendment may be made that would:

•enlarge the obligations of any limited partner without its consent, unless approved by at least a majority of the type or class of limited partner interests so affected;

•enlarge the obligations of, restrict in any way any action by or rights of, or reduce in any way the amounts distributable, reimbursable or otherwise payable by us to our general partner or any of its affiliates without the consent of our general partner, which may be given or withheld in its sole discretion;

•change the duration of our partnership;

•provide that our partnership is not dissolved upon an election to dissolve our partnership by our general partner that is approved by a unit majority; or;

•give any person the right to dissolve our partnership other than our general partner’s right to dissolve our partnership with the approval of a unit majority.

The provision of our Partnership Agreement preventing the amendments having the effects described in any of the clauses above can be amended upon the approval of the holders of at least 90% of the outstanding units voting together as a single class.

Additionally, our general partner may generally make amendments to our Partnership Agreement without the approval of any limited partner in certain circumstances.

Assuming that a limited partner does not participate in the control of our business within the meaning of the Delaware Act and that it otherwise acts in conformity with the provisions of our Partnership Agreement, its liability under the Delaware Act will be limited, subject to possible exceptions, to the amount of capital it is obligated to contribute to us for its common units plus its share of any undistributed profits and assets.

Subject to certain limitations, our Partnership Agreement authorizes us to issue an unlimited number of additional partnership interests and options, rights, warrants and appreciation rights relating to the partnership interests for any partnership purpose at any time and from time to time to such persons for such consideration and on such terms and conditions as our general partner shall determine in its sole discretion, all without the approval of any partners.

In accordance with Delaware law and the provisions of our Partnership Agreement, we may also issue additional partnership interests that, as determined by our general partner, may have special voting rights to which the common units are not entitled.

Our Partnership Agreement contains specific provisions that are intended to discourage a person or group from attempting to remove Martin Midstream GP LLC as our general partner or otherwise change our management. If any person or group other than our general partner and its affiliates acquires beneficial ownership of 20% or more of any class of units, that person or group loses voting rights on all of its units. This loss of voting rights does not apply to any person or group that acquires the units from our general partner or its affiliates and any transferees of that person or group who are notified by our general partner that they will not lose their voting rights or to any person or group who acquires the units with the prior approval of the board of directors of our general partner.

If at any time our general partner and its affiliates own more than 80% of the then-issued and outstanding limited partner interests of any class, our general partner will have the right, which it may assign in whole or in part to any of its affiliates or to us, to acquire all, but not less than all, of the limited partner interests of such class held by unaffiliated persons as of a record date to be selected by our general partner, on at least 10, but not more than 60, days’ written notice.

Our Partnership Agreement states that we will mail or make available to record holders of common units, within 120 days after the close of each fiscal year, an annual report containing audited financial statements and a report on those financial statements by our independent public accountants. Except for our fourth quarter, we will also mail or make available summary financial information within 90 days after the close of each quarter. We will furnish each record holder of a unit with information reasonably required for tax reporting purposes within 90 days after the close of each calendar year.

In addition to information that a limited partner would otherwise have under Delaware law, our Partnership Agreement provides that a limited partner can, for a purpose reasonably related to its interest as a limited partner, upon reasonable written demand stating the purpose of such demand and at its own expense, have furnished to such limited partner, certain information regarding the status of our business and financial condition, in addition to certain information related to our record holders.