Warrant to purchase stock issued to Silicon Valley Bank, dated May 14, 2019

Exhibit 4.3

THIS WARRANT AND THE SHARES ISSUABLE HEREUNDER HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “ACT”), OR THE SECURITIES LAWS OF ANY STATE AND, EXCEPT AS SET FORTH IN SECTIONS 5.3 AND 5.4 BELOW, MAY NOT BE OFFERED, SOLD, PLEDGED OR OTHERWISE TRANSFERRED UNLESS AND UNTIL REGISTERED UNDER SAID ACT AND LAWS OR, IN THE OPINION OF LEGAL COUNSEL IN FORM AND SUBSTANCE SATISFACTORY TO THE ISSUER, SUCH OFFER, SALE, PLEDGE OR OTHER TRANSFER IS EXEMPT FROM SUCH REGISTRATION.

WARRANT TO PURCHASE STOCK

Company: Phathom Pharmaceuticals, Inc., a Delaware corporation

Number of Shares: As set forth in Paragraph A below

Type/Series of Stock: As set forth in Paragraph A below

Warrant Price: As set forth in Paragraph A below

Issue Date: May 14, 2019

Expiration Date: As set forth in Section 5.1(a) below.

THIS WARRANT CERTIFIES THAT, for good and valuable consideration, SILICON VALLEY BANK (together with any successor or permitted assignee or transferee of this Warrant or of any shares issued upon exercise hereof, “Holder”) is entitled to purchase up to the number of fully paid and non-assessable shares of the above-stated Type/Series of Stock (the “Class”) of the above-named company (the “Company”) determined pursuant to Paragraph A below, at a purchase price per share equal to the Warrant Price (as defined below), all as set forth above and as adjusted pursuant to Section 2 of this Warrant, subject to the provisions and upon the terms and conditions set forth in this Warrant. Reference is made to Section 5.4 of this Warrant whereby Silicon Valley Bank shall transfer this Warrant to its parent company, SVB Financial Group.

A.    Number of Shares; Warrant Price; Class.

(1)     Number of Shares. Upon the making (if any) of each Term B Loan Advance (as defined in the Loan Agreement), this Warrant automatically shall become exercisable for such number of shares of the Class (cumulatively and collectively, and as may be adjusted from time to time in accordance with the provisions of this Warrant, the “Shares”) as shall equal (a)(i) 0.01, multiplied by (ii) the amount of such Term B Loan Advance, divided by (b) the Warrant Price in effect on and as of the date of such Term B Loan Advance, subject to adjustment thereafter from time to time in accordance with the provisions of this Warrant.

(2)     Warrant Price. The purchase price per Share hereunder (the “Warrant Price”) shall equal the Note Conversion Price (as defined below), subject to adjustment from time to time in accordance with the provisions of this Warrant.

(3)     Certain Definitions. As used herein, the following capitalized terms have the respective meanings given below:

“Class” means Qualified Financing Securities.

“Note Conversion Price” means the “Conversion Price” (as defined in the Note Purchase Agreement) at which the Notes convert into shares or units of Qualified Financing Securities, or otherwise for which shares or units of Qualified Financing Securities are issued by the Company in exchange for, or in satisfaction of its obligations under, the Notes in the Qualified Financing.

“Note Purchase Agreement” means that certain Note Purchase Agreement of the Company dated May 7, 2019 among the Company and the several purchasers named therein, as amended and/or restated and in effect from time to time.

“Notes” means those certain convertible promissory notes of the Company issued from time to time under and pursuant to the Note Purchase Agreement, as any or all of such notes may be amended and/or restated and in effect from time to time, together with any convertible promissory notes of the Company issued in exchange for, or replacement or substitution of, such notes.

“Qualified Financing” means the first to occur of (a) a “Next Equity Financing,” (b) a “Non-Qualified Next Equity Financing” or (c) an “Initial Public Offering” (each as defined in the Note Purchase Agreement), in each case in which the Notes convert into, or are otherwise exchanged for or satisfied by the Company’s issuance of, Qualified Financing Securities.

“Qualified Financing Securities” means the class and/or series and/or other designation of Company capital stock and/or other equity securities sold and issued by the Company in the Qualified Financing.

SECTION 1. EXERCISE.

1.1    Method of Exercise. Holder may at any time and from time to time on or after the first date (if any) on which a Term B Loan Advance shall be made to the Company and on or before the Expiration Date, exercise this Warrant, in whole or in part, by delivering to the Company the original of this Warrant together with a duly executed Notice of Exercise in substantially the form attached hereto as Appendix 1 and, unless Holder is exercising this Warrant pursuant to a cashless exercise set forth in Section 1.2, a check, wire transfer of same-day funds (to an account designated by the Company), or other form of payment acceptable to the Company for the aggregate Warrant Price for the Shares being purchased.

1.2    Cashless Exercise. On any exercise of this Warrant, in lieu of payment of the aggregate Warrant Price in the manner as specified in Section 1.1 above, but otherwise in accordance with the requirements of Section 1.1, Holder may elect to receive Shares equal to the value of this Warrant, or portion hereof as to which this Warrant is being exercised. Thereupon, the Company shall issue to the Holder such number of fully paid and non-assessable Shares as are computed using the following formula:

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1.3    Fair Market Value. If the Company’s common stock is then traded or quoted on a nationally recognized securities exchange, inter-dealer quotation system or over-the-counter market (a “Trading Market”) and the Class is common stock, the fair market value of a Share shall be the closing price or last sale price of a share of common stock reported for the Business Day immediately before the date on which Holder delivers this Warrant together with its Notice of Exercise to the Company. If the Company’s common stock is then traded in a Trading Market and the Class is a series of the Company’s convertible preferred stock, the fair market value of a Share shall be the closing price or last sale price of a share of the Company’s common stock reported for the Business Day immediately before the date on which Holder delivers this Warrant together with its Notice of Exercise to the Company multiplied by the number of shares of the Company’s common stock into which a Share is then convertible. If the Company’s common stock is not traded in a Trading Market, the Board of Directors of the Company shall determine the fair market value of a Share in its reasonable good faith judgment.

1.4    Delivery of Book Entry Statement or Certificate and New Warrant. Within a reasonable time after Holder exercises this Warrant in the manner set forth in Section 1.1 or 1.2 above, the Company or its transfer agent shall deliver to Holder a book entry statement or certificate representing the Shares issued to Holder upon such exercise and, if this Warrant has not been fully exercised and has not expired, a new warrant of like tenor representing the Shares not so acquired.

1.5    Replacement of Warrant. On receipt of evidence reasonably satisfactory to the Company of the loss, theft, destruction or mutilation of this Warrant and, in the case of loss, theft or destruction, on delivery of an indemnity agreement reasonably satisfactory in form, substance and amount to the Company or, in the case of mutilation, on surrender of this Warrant to the Company for cancellation, the Company shall, within a reasonable time, execute and deliver to Holder, in lieu of this Warrant, a new warrant of like tenor and amount.

1.6    Treatment of Warrant Upon Acquisition of Company.

(a)    Acquisition. For the purpose of this Warrant, “Acquisition” means any transaction or series of related transactions involving: (i) the sale, lease, exclusive license, or other disposition of all or substantially all of the assets of the Company; (ii) any merger or consolidation of the Company into or with another person or entity (other than a merger or consolidation effected exclusively to change the Company’s domicile), or any other corporate reorganization, in which the stockholders of the Company in their capacity as such immediately prior to such merger, consolidation or reorganization, own less than a majority of the Company’s (or the surviving or successor entity’s) outstanding voting power immediately after such merger, consolidation or reorganization); (iii) any merger or consolidation of the Company into or with another person or entity, or any other corporate reorganization, in which (A) the stockholders of the Company in their capacity as such immediately prior to such merger, consolidation or

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reorganization, own a majority of the outstanding voting power of the surviving or successor entity as of immediately after such merger, consolidation or reorganization, and (B) such surviving or successor entity is not the Company; or (iv) any sale or other transfer by the stockholders of the Company of shares representing at least a majority of the Company’s then-total outstanding combined voting power. For the avoidance of doubt, “Acquisition” shall not include any sale and issuance by the Company of shares of its capital stock or of securities or instruments exercisable for or convertible into, or otherwise representing the right to acquire, shares of its capital stock to one or more investors for cash and/or conversion or cancellation of indebtedness in a transaction or series of related transactions the primary purpose of which is a bona fide equity financing of the Company.

(b)    Treatment of Warrant at Acquisition. In the event of an Acquisition in which the consideration to be received by the Company’s stockholders consists solely of cash, solely of Marketable Securities or a combination of cash and Marketable Securities (a “Cash/Public Acquisition”), and the fair market value of one Share as determined in accordance with Section 1.3 above would be greater than the Warrant Price in effect on such date immediately prior to such Cash/Public Acquisition, and Holder has not exercised this Warrant pursuant to Section 1.1 above as to all Shares, then this Warrant shall automatically be deemed to be Cashless Exercised pursuant to Section 1.2 above as to all Shares effective immediately prior to and contingent upon the consummation of a Cash/Public Acquisition. In connection with such Cashless Exercise, Holder shall be deemed to have restated each of the representations and warranties in Section 4 of the Warrant as of the date thereof and the Company shall promptly notify the Holder of the number of Shares (or such other securities) issued upon exercise. In the event of a Cash/Public Acquisition where the fair market value of one Share as determined in accordance with Section 1.3 above would be less than the Warrant Price in effect immediately prior to such Cash/Public Acquisition, then this Warrant will expire immediately prior to the consummation of such Cash/Public Acquisition.

(c)     Upon the closing of any Acquisition other than a Cash/Public Acquisition, the acquiring, surviving or successor entity shall assume the obligations of this Warrant, and this Warrant shall thereafter be exercisable for the same securities and/or other property as would have been paid for the Shares issuable upon exercise of the unexercised portion of this Warrant as if such Shares were outstanding on and as of the closing of such Acquisition, subject to further adjustment from time to time in accordance with the provisions of this Warrant.

(d)    As used in this Warrant, “Marketable Securities” means securities meeting all of the following requirements: (i) the issuer thereof is then subject to the reporting requirements of Section 13 or Section 15(d) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and is then current in its filing of all required reports and other information under the Act and the Exchange Act; (ii) the class and series of shares or other security of the issuer that would be received by Holder in connection with the Acquisition were Holder to exercise this Warrant on or prior to the closing thereof is then traded in a Trading Market, and (iii) following the closing of such Acquisition, Holder would not be restricted from publicly re-selling all of the issuer’s shares and/or other securities that would be received by Holder in such Acquisition were Holder to exercise this Warrant in full on or prior to the closing of such Acquisition, except to the extent that any such restriction (x) arises solely under federal or state securities laws, rules or regulations, and (y) does not extend beyond six (6) months from the closing of such Acquisition.

1.7    Holder Put Right. Notwithstanding the provisions of Section 1.6 above or any other provision of this Warrant to the contrary, in the event that there shall be no Term B Loan Advance

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made to the Company on or before March 31, 2020, for any reason or no reason (other than by default of any Lender party under the Loan Agreement), including, without limitation, the Company’s failure or inability to consummate the Qualified Financing on or before such date, Holder shall have the one-time right (but not the obligation) (the “Put Right”), exercisable in its sole discretion upon written notice to the Company (the “Put Notice”) given at any time within six (6) months after such date, to require the Company to repurchase from Holder all (but not less than all) of this Warrant (and the Company hereby agrees to repurchase this Warrant from Holder upon Holder’s exercise of such Put Right) for a total aggregate purchase price of $250,000 (the “Repurchase Price”), such Repurchase Price to be paid by the Company to Holder in cash in a single installment of immediately available funds at the Put Closing (as defined below), against surrender by Holder to the Company thereat of the original of this Warrant, duly endorsed for transfer on the books of the Company or accompanied by duly executed stock powers and/or other instruments of assignment or transfer. As used in this Section 1.7, “Put Closing” means the closing of the Company’s repurchase of this Warrant pursuant to Holder’s exercise of its Put Right, to be held at the principal office of the Company on such date as shall be set forth in Holder’s Put Notice, which date shall be not less than ten (10) days following the date of such Put Notice.

Notwithstanding anything in this Warrant to the contrary, (1) upon Holder’s delivery of the Put Notice, but subject to the consummation of the Company’s repurchase of this Warrant at the Put Closing in accordance with the requirements of this Section 1.7, this Warrant shall cease to be exercisable for any Shares, and (2) upon the consummation of the Company’s repurchase of this Warrant at the Put Closing in accordance with the requirements of this Section 1.7, this Warrant shall terminate and be of no further force or effect.

SECTION 2. ADJUSTMENTS TO THE SHARES AND WARRANT PRICE.

2.1    Stock Dividends, Splits, Etc. If the Company declares or pays a dividend or distribution on the outstanding shares of the Class payable in additional shares of the Class or other securities or property (other than cash), then upon exercise of this Warrant, for each Share acquired, Holder shall receive, without additional cost to Holder, the total number and kind of securities and property which Holder would have received had Holder owned the Shares of record as of the date the dividend or distribution occurred. If the Company subdivides the outstanding shares of the Class by reclassification or otherwise into a greater number of shares, the number of Shares purchasable hereunder shall be proportionately increased and the Warrant Price shall be proportionately decreased. If the outstanding shares of the Class are combined or consolidated, by reclassification or otherwise, into a lesser number of shares, the Warrant Price shall be proportionately increased and the number of Shares shall be proportionately decreased.

2.2    Reclassification, Exchange, Combinations or Substitution. Upon any event whereby all of the outstanding shares of the Class are reclassified, exchanged, combined, substituted, or replaced for, into, with or by Company securities of a different class and/or series (including, without limitation, if the Class is a series of the Company’s convertible preferred stock, the conversion of all outstanding shares of such Class into common stock in accordance with the Company’s Amended and Restated Certificate of Incorporation, as amended and/or restated and in effect from time to time (the “COI”)), then from and after the consummation of such event, this Warrant will be exercisable for the number, class and series of Company securities that Holder would have received had the Shares been outstanding on and as of the consummation of such event, and subject to further adjustment thereafter from time to time in accordance with the provisions of this Warrant. The provisions of this Section 2.2

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shall similarly apply to successive reclassifications, exchanges, combinations, substitutions, replacements or other similar events.

2.3    No Fractional Share. No fractional Share shall be issuable upon exercise of this Warrant and the number of Shares to be issued shall be rounded down to the nearest whole Share. If a fractional Share interest arises upon any exercise of the Warrant, the Company shall eliminate such fractional Share interest by paying Holder in cash the amount computed by multiplying the fractional interest by (i) the fair market value (as determined in accordance with Section 1.3 above) of a full Share, less (ii) the then-effective Warrant Price.

2.4    Notice/Certificate as to Adjustments. Upon each adjustment of the Warrant Price, Class and/or number of Shares, the Company, at the Company’s expense, shall notify Holder in writing within a reasonable time setting forth the adjustments to the Warrant Price, Class and/or number of Shares and facts upon which such adjustment is based. The Company shall, upon written request from Holder, furnish Holder with a certificate of its Chief Financial Officer, including computations of such adjustment and the Warrant Price, Class and number of Shares in effect upon the date of such adjustment.

2.5    Adjustments for Diluting Issuances. Without duplication of any adjustment otherwise provided for in this Section 2, if the Class is a series of the Company’s convertible preferred stock, then the number of shares of common stock issuable upon conversion of the Shares shall be subject to anti-dilution adjustment from time to time in the manner applicable to the outstanding shares of the Class as set forth in the COI as if the Shares were issued and outstanding on and as of the date of any such required adjustment.

SECTION 3. REPRESENTATIONS AND COVENANTS OF THE COMPANY.

3.1    Representations and Warranties. The Company represents and warrants to, and agrees with, the Holder as follows:

(a)    [Reserved].

(b)    All Shares which may be issued upon the exercise of this Warrant shall, upon issuance, be duly authorized, validly issued, fully paid and non-assessable, and free of any liens and encumbrances except for restrictions on transfer provided for herein or under applicable federal and state securities laws. The Company covenants that it shall at all times cause to be reserved and kept available out of its authorized and unissued capital stock such number of shares of the Class and other securities as will be sufficient to permit the exercise in full of this Warrant.

(c)    The Company’s capitalization table attached hereto as Schedule 1 is true and complete, in all material respects, as of the Issue Date.

3.2    Notice of Certain Events. At all times prior to the IPO while this Warrant shall then be exercisable for any Shares in accordance with its terms, if the Company proposes at any time to:

(a)    declare any dividend or distribution upon the outstanding shares of the Class, whether in cash, property, stock, or other securities and whether or not a regular cash dividend;

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(b)    offer for subscription or sale pro rata to the holders of the outstanding shares of the Class any additional shares of any class or series of the Company’s stock (other than pursuant to contractual pre-emptive rights);

(c)    effect any reclassification, exchange, combination, substitution, reorganization or recapitalization of the outstanding shares of the Class;

(d)    effect an Acquisition or to liquidate, dissolve or wind up; or

(e)    effect its initial, underwritten offering and sale of its securities to the public pursuant to an effective registration statement under the Act (the “IPO”);

then, in connection with each such event, the Company shall give Holder:

(1)    in the case of the matters referred to in (a) and (b) above, at least seven (7) Business Days prior written notice of the earlier to occur of the effective date thereof or the date on which a record will be taken for such dividend, distribution, or subscription rights (and specifying the date on which the holders of outstanding shares of the Class will be entitled thereto) or for determining rights to vote, if any;

(2)    in the case of the matters referred to in (c) and (d) above at least seven (7) Business Days prior written notice of the date when the same will take place (and specifying the date on which the holders of outstanding shares of the Class will be entitled to exchange their shares for the securities or other property deliverable upon the occurrence of such event and such reasonable information as Holder may reasonably require regarding the treatment of this Warrant in connection with such event giving rise to the notice); and

(3)    with respect to the IPO, at least seven (7) Business Days prior written notice of the date on which the Company proposes to file its registration statement in connection therewith.

The Company will also provide information requested by Holder from time to time, within a reasonable time following each such request, that is reasonably necessary to enable Holder to comply with Holder’s accounting or reporting requirements. Prior to the IPO, such information may include, but shall not be limited to, the Company’s then-current summary capitalization table, the price per share for which the Company most recently prior thereto sold or issued shares of its convertible preferred stock to investors for cash in a bona fide equity financing of the Company, and the Company’s most recent valuation of a share of its common stock pursuant to Section 409A of the Internal Revenue Code of 1986, as amended. Holder agrees to treat and hold all information provided by the Company pursuant to this Warrant in confidence in accordance with the provisions of Section 12.9 of the Loan Agreement (regardless of whether the Loan Agreement shall then be in effect).

SECTION 4. REPRESENTATIONS, WARRANTIES OF THE HOLDER.

The Holder represents and warrants to the Company as follows:

4.1    Purchase for Own Account. This Warrant and the Shares to be acquired upon exercise of this Warrant by Holder are being acquired for investment for Holder’s account, not as a nominee or agent, and not with a view to the public resale or distribution within the meaning of the Act.

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Holder also represents that it has not been formed for the specific purpose of acquiring this Warrant or the Shares.

4.2    Disclosure of Information. Holder is aware of the Company’s business affairs and financial condition and has received or has had full access to all the information it considers necessary or appropriate to make an informed investment decision with respect to the acquisition of this Warrant and its underlying securities. Holder further has had an opportunity to ask questions and receive answers from the Company regarding the terms and conditions of the offering of this Warrant and its underlying securities and to obtain additional information (to the extent the Company possessed such information or could acquire it without unreasonable effort or expense) necessary to verify any information furnished to Holder or to which Holder has access.

4.3    Investment Experience. Holder understands that the purchase of this Warrant and its underlying securities involves substantial risk. Holder has experience as an investor in securities of companies in the development stage and acknowledges that Holder can bear the economic risk of such Holder’s investment in this Warrant and its underlying securities and has such knowledge and experience in financial or business matters that Holder is capable of evaluating the merits and risks of its investment in this Warrant and its underlying securities and/or has a preexisting personal or business relationship with the Company and certain of its officers, directors or controlling persons of a nature and duration that enables Holder to be aware of the character, business acumen and financial circumstances of such persons.

4.4    Accredited Investor Status. Holder is an “accredited investor” within the meaning of Regulation D promulgated under the Act.

4.5    The Act. Holder understands that this Warrant and the Shares issuable upon exercise hereof have not been registered under the Act in reliance upon a specific exemption therefrom, which exemption depends upon, among other things, the bona fide nature of the Holder’s investment intent as expressed herein. Holder understands that this Warrant and the Shares issued upon any exercise hereof must be held indefinitely unless subsequently registered under the Act and qualified under applicable state securities laws, or unless exemption from such registration and qualification are otherwise available. Holder is aware of the provisions of Rule 144 promulgated under the Act.

4.6    No Voting Rights. Holder, as a Holder of this Warrant, will not have any voting rights until the exercise of this Warrant.

4.7    Market Stand Off. Holder hereby agrees that it will not, without the prior written consent of the managing underwriter, during the period commencing on the date of the final prospectus relating to the IPO and ending on the date specified by the Company and the managing underwriter (such period not to exceed one hundred eighty (180) days) (a) lend, offer, pledge, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase, or otherwise transfer or dispose of, directly or indirectly, any Shares held immediately prior to the effectiveness of the registration statement for such offering, or (b) enter into any swap or other arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of the Shares, whether any such transaction described in clause (a) or (b) above is to be settled by delivery of the Shares or other securities, in cash or otherwise. The foregoing provisions of this Section 4.7 shall apply only to the Company’s IPO, shall not apply to the sale of any shares to an underwriter pursuant to an underwriting agreement, and shall not apply unless all directors and officers of the Company, and all holders of one percent (1%) or more of the Company’s outstanding common stock determined on a fully-

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diluted, as-exercised, as-converted basis, are then bound by substantially similar written agreements with the Company and/or the underwriters in connection with the Company’s IPO. The underwriters in connection with the Company’s IPO are intended third-party beneficiaries of this Section 4.7 and shall have the right, power and authority to enforce the provisions hereof as though they were a party hereto. Holder further agrees to execute such agreements as may be reasonably requested by the underwriters in the Company’s IPO that are consistent with this Section 4.7 or that are necessary to give further effect thereto. In order to enforce the foregoing covenant, the Company may impose stop-transfer instructions with respect to the Shares (and the shares or securities of every other person subject to the foregoing restriction) until the end of such period.

SECTION 5. MISCELLANEOUS.

5.1    Term; Automatic Cashless Exercise Upon Expiration.

(a)     Term. Subject to the provisions of Section 1.6 above, this Warrant is exercisable in whole or in part at any time and from time to time commencing on the first date (if any) on which a Term B Loan Advance shall be made to the Company and ending on or before 6:00 PM, Pacific time, on the tenth (10th) anniversary of the Issue Date hereof (the “Expiration Date”) and shall be void thereafter; provided, that if there shall have been no Term B Loan Advance made to the Company on or before March 31, 2020 for any reason or no reason (other than by default of any Lender party under the Loan Agreement), including, without limitation, the Company’s failure or inability to consummate the Qualified Financing on or before such date, then, subject to the provisions of Section 1.7 above, this Warrant shall terminate on September 30, 2020 unless Holder shall have delivered a Put Notice on or before such date, in which case this Warrant shall terminate upon consummation of the Company’s repurchase of this Warrant at the Put Closing in accordance with the requirements of Section 1.7 above.

(b)    Automatic Cashless Exercise upon Expiration. In the event that, upon the Expiration Date, the fair market value of one Share as determined in accordance with Section 1.3 above is greater than the Warrant Price in effect on such date, then this Warrant shall automatically be deemed on and as of such date to be exercised pursuant to Section 1.2 above as to all Shares for which it shall not previously have been exercised, and the Company shall, within a reasonable time, deliver a certificate representing the Shares issued upon such exercise to Holder.

5.2    Legends. Each certificate evidencing Shares shall be imprinted with a legend in substantially the following form:

THE SHARES EVIDENCED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “ACT”), OR THE SECURITIES LAWS OF ANY STATE AND, EXCEPT AS SET FORTH IN THAT CERTAIN WARRANT TO PURCHASE STOCK ISSUED BY THE ISSUER TO SILICON VALLEY BANK DATED MAY 14, 2019, MAY NOT BE OFFERED, SOLD, PLEDGED OR OTHERWISE TRANSFERRED UNLESS AND UNTIL REGISTERED UNDER SAID ACT AND LAWS OR, IN THE OPINION OF LEGAL COUNSEL IN FORM AND SUBSTANCE SATISFACTORY TO THE ISSUER, SUCH OFFER, SALE, PLEDGE OR OTHER TRANSFER IS EXEMPT FROM SUCH REGISTRATION.

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And, if then applicable, a legend in substantially the following form:

THE SHARES EVIDENCED BY THIS CERTIFICATE ARE SUBJECT TO A LOCK-UP PERIOD AFTER THE EFFECTIVE DATE OF THE ISSUER’S REGISTRATION STATEMENT FILED UNDER THE SECURITIES ACT, AS AMENDED, AS SET FORTH IN AN AGREEMENT BETWEEN THE COMPANY AND THE ORIGINAL HOLDER OF THESE SECURITIES, A COPY OF WHICH MAY BE OBTAINED AT THE ISSUER’S PRINCIPAL OFFICE. SUCH LOCK-UP PERIOD IS BINDING ON TRANSFEREES OF THESE SHARES.

5.3    Compliance with Securities Laws on Transfer. This Warrant and the Shares issued upon exercise of this Warrant may not be transferred or assigned in whole or in part except in compliance with applicable federal and state securities laws by the transferor and the transferee (including, without limitation, the delivery of investment representation letters and legal opinions reasonably satisfactory to the Company, as reasonably requested by the Company). The Company shall not require Holder to provide an opinion of counsel if the transfer is to SVB Financial Group (Silicon Valley Bank’s parent company) or any other affiliate of Holder, provided that any such transferee is an “accredited investor” as defined in Regulation D promulgated under the Act.

5.4    Transfer Procedure. After receipt by Silicon Valley Bank of the executed Warrant, Silicon Valley Bank will transfer all of this Warrant to its parent company, SVB Financial Group. By its acceptance of this Warrant, SVB Financial Group hereby makes to the Company each of the representations and warranties set forth in Section 4 hereof and agrees to be bound by all of the terms and conditions of this Warrant as if the original Holder hereof. Subject to the provisions of Section 5.3 and upon providing the Company with written notice, SVB Financial Group and any subsequent Holder may transfer all or part of this Warrant or the Shares issued upon exercise of this Warrant to any transferee, provided, however, in connection with any such transfer, SVB Financial Group or any subsequent Holder will give the Company notice of the portion of the Warrant and/or Shares being transferred with the name, address and taxpayer identification number of the transferee and Holder will surrender this Warrant to the Company for reissuance to the transferee(s) (and Holder if applicable); and provided further, that any subsequent transferee other than SVB Financial Group shall agree in writing with the Company to be bound by all of the terms and conditions of this Warrant. Notwithstanding any contrary provision herein, at all times prior to the IPO, Holder may not, without the Company’s prior written consent, transfer this Warrant or any portion hereof, or any Shares issued upon any exercise hereof, to any person or entity who directly competes with the Company, except in connection with an Acquisition of the Company by such a direct competitor.

5.5    Notices. All notices and other communications hereunder from the Company to the Holder, or vice versa, shall be deemed delivered and effective (i) when given personally, (ii) on the third (3^rd) Business Day after being mailed by first-class registered or certified mail, postage prepaid, (iii) upon actual receipt if given by facsimile or electronic mail and such receipt is confirmed in writing by the recipient, or (iv) on the first Business Day following delivery to a reliable overnight courier service, courier fee prepaid, in any case at such address as may have been furnished to the Company or Holder, as the case may be, in writing by the Company or such Holder from time to time in accordance with the provisions of this Section 5.5. All notices to Holder shall be addressed as follows until the Company receives notice of a change of address in connection with a transfer or otherwise:

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SVB Financial Group

Attn: Treasury Department

3003 Tasman Drive, HC 215

Santa Clara, CA 95054

Telephone:

Facsimile:

Email address:

Notice to the Company shall be addressed as follows until Holder receives notice of a change in address:

Phathom Pharmaceuticals, Inc.

Attn: Chief Financial Officer

60 Willow Road, Suite 200

Menlo Park, CA 940025

Telephone:

Facsimile:

Email:

With a copy (which shall not constitute notice) to:

Latham & Watkins LLP

12670 High Bluff Drive

San Diego, CA 92103

Attention: Cheston J. Larson

Email: ***@***

Facsimile No.: (858) 523-5450

5.6    Waiver. This Warrant and any term hereof may be changed, waived, discharged or terminated (either generally or in a particular instance and either retroactively or prospectively) only by an instrument in writing signed by the party against which enforcement of such change, waiver, discharge or termination is sought.

5.7    Attorneys’ Fees. In the event of any dispute between the parties concerning the terms and provisions of this Warrant, the party prevailing in such dispute shall be entitled to collect from the other party all costs incurred in such dispute, including reasonable attorneys’ fees.

5.8    Counterparts; Facsimile/Electronic Signatures. This Warrant may be executed in counterparts, all of which together shall constitute one and the same agreement. Any signature page delivered electronically or by facsimile shall be binding to the same extent as an original signature page with regards to any agreement subject to the terms hereof or any amendment thereto.

5.9    Governing Law. This Warrant shall be governed by and construed in accordance with the laws of the State of California, without giving effect to its principles regarding conflicts of law.

5.10    Headings. The headings in this Warrant are for purposes of reference only and shall not limit or otherwise affect the meaning of any provision of this Warrant.

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5.11    Business Days. “Business Day” is any day that is not a Saturday, Sunday or a day on which Silicon Valley Bank is closed.

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IN WITNESS WHEREOF, the parties have caused this Warrant to Purchase Stock to be executed by their duly authorized representatives effective as of the Issue Date written above.

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APPENDIX 1

NOTICE OF EXERCISE

1.    The undersigned Holder hereby exercises its right to purchase                  shares of the Common/Series                      Preferred [circle one] Stock of                      (the “Company”) in accordance with the attached Warrant To Purchase Stock, and tenders payment of the aggregate Warrant Price for such shares as follows:

2.    Please issue a certificate or certificates representing the Shares in the name specified below:

3.    By its execution below and for the benefit of the Company, Holder hereby restates each of the representations and warranties in Section 4 of the Warrant to Purchase Stock as of the date hereof.

Appendix 1