Form 8-K

8-K — Outlook Therapeutics, Inc.

Accession: 0001104659-26-068306

Filed: 2026-05-29

Period: 2026-05-29

CIK: 0001649989

SIC: 2836 (BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES))

Item: Other Events

Item: Financial Statements and Exhibits

Documents

8-K — tm2615979d1_8k.htm (Primary)

EX-5.1 — EXHIBIT 5.1 (tm2615979d1_ex5-1.htm)

GRAPHIC (tm2615979d1_ex5-1img01.jpg)

XML — IDEA: XBRL DOCUMENT (R1.htm)

8-K — FORM 8-K

8-K (Primary)

Filename: tm2615979d1_8k.htm · Sequence: 1

false

0001649989

2026-05-29

iso4217:USD

xbrli:shares

iso4217:USD

xbrli:shares

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13

OR 15(d) of The Securities Exchange Act of 1934

Date of Report (Date

of earliest event reported): May 29, 2026

Outlook Therapeutics,

Inc.

(Exact name of registrant

as specified in its charter)

Delaware

001-37759

38-3982704

(State or other jurisdiction

of incorporation)

(Commission File Number)

(IRS Employer Identification No.)

111

S. Wood Avenue, Unit

#100

Iselin, New Jersey

08830

(Address of principal executive offices)

(Zip Code)

Registrant's telephone number, including area code:

(609) 619-3990

Check the appropriate box below if the Form 8-K

filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities pursuant to Section 12(b) of the Act:

Title of Each Class

Trading Symbol(s)

Name of Each Exchange

on Which

Registered

Common Stock

OTLK

The Nasdaq Stock Market LLC

Indicate by check mark whether the registrant is an emerging growth

company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange

Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ¨

If an emerging growth company, indicate by check mark if the registrant

has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant

to Section 13(a) of the Exchange Act. ¨

Item 8.01

Other Events.

Exhibits are filed herewith in connection with

the registered direct offering (the “Registered Direct Offering”) by Outlook Therapeutics, Inc. (the “Company”)

of 8,539,709 shares of the Company’s common stock, $0.01 par value per share, to GMS Ventures and Investments (the “Purchaser”)

pursuant to that certain securities purchase agreement entered into on May 28, 2026, by and between the Company and the Purchaser. The Registered

Direct Offering was made pursuant to the Company’s effective registration statement on Form S-3 (File No. 333-278340) that

was originally filed with the Securities and Exchange Commission on March 28, 2024 and which became effective on April 5, 2024 and a related

base prospectus and prospectus supplement thereunder.

Item 9.01

Financial Statements and Exhibits

(d) Exhibits

Exhibit No.

Description

5.1

Opinion of Cooley, dated May 29, 2026.

23.1

Consent of Cooley LLP (included in Exhibit 5.1).

104

Cover Page Interactive Data File (embedded within the Inline XBRL document).

SIGNATURES

Pursuant to the requirements of the Securities

Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Outlook Therapeutics, Inc.

Date: May 29, 2026

By:

/s/ Lawrence A. Kenyon

Lawrence A. Kenyon

Chief Financial Officer

EX-5.1 — EXHIBIT 5.1

EX-5.1

Filename: tm2615979d1_ex5-1.htm · Sequence: 2

Exhibit 5.1

Yvan-Claude Pierre

+1 212 479-6721

ypierre@cooley.com

May 29, 2026

Outlook Therapeutics, Inc.

111 S. Wood Ave., Unit #100

Iselin, NJ 08830

Ladies and Gentlemen:

We have acted as counsel to Outlook Therapeutics,

Inc., a Delaware corporation (the “Company”), in connection with the offering by the Company of 8,539,709 shares

(the “Shares”) of its common stock, par value $0.01 per share (the “Common Stock”)

pursuant to a Registration Statement on Form S-3 (File No. 333-278340) (the “Registration Statement”) filed

by the Company with the Securities and Exchange Commission (the “Commission”) under the Securities Act of 1933,

as amended (the “Securities Act”), the base prospectus included in the Registration Statement (the “Base

Prospectus”), and the related prospectus supplement filed with the Commission pursuant to Rule 424 under the Securities

Act (together with the Base Prospectus, the “Prospectus”).

In connection with this opinion, we have examined

and relied upon the Registration Statement, the Prospectus, the Company’s certificate of incorporation and bylaws, each as currently

in effect, and such other records, documents, opinions, certificates, memoranda and instruments as in our judgment are necessary or appropriate

to enable us to render the opinion expressed below. We have assumed the genuineness of all signatures, the authenticity of all documents

submitted to us as originals, the conformity to originals of all documents submitted to us as copies; the accuracy, completeness and authenticity

of certificates of public officials, and the due authorization, execution and delivery of all documents by all persons other than the

Company. As to certain factual matters, we have relied upon a certificate of an officer of the Company and have not independently verified

such matters.

Our opinion is expressed solely with respect to

the General Corporation Law of the State of Delaware. We express no opinion to the extent that any other laws are applicable to the subject

matter hereof and express no opinion and provide no assurance as to compliance with any federal or state securities law, rule or regulation.

On the basis of the foregoing, in reliance thereon

and subject to the qualifications set forth herein, we are of the opinion that the Shares, when sold and issued against payment therefor

in accordance with the Registration Statement and the Prospectus, will be validly issued, fully paid and nonassessable.

This opinion is limited to the matters expressly

set forth in this letter, and no opinion has been or should be implied, or may be inferred, beyond the matters expressly stated. This

opinion speaks only as to law and facts in effect or existing as of the date hereof and we have no obligation or responsibility to update

or supplement this letter to reflect any facts or circumstances that may hereafter come to our attention or any changes in law that may

hereafter occur.

Cooley

LLP 1299 Pennsylvania Avenue NW Suite 700 Washington, DC 20004-2400

+1 202 842 7800 f: +1 202 842 7899 cooley.com

Outlook Therapeutics, Inc.

May 29, 2026

Page Two

We consent to the reference to our firm under

the heading “Legal Matters” in the Prospectus and to the filing of this opinion as an exhibit to the Company’s Current

Report on Form 8-K to be filed with the Commission for incorporation by reference into the Registration Statement. In giving such consents,

we do not thereby admit that we are in the category of persons whose consent is required under Section 7 of the Securities Act or the

rules and regulations of the Commission thereunder.

Very truly yours,

Cooley LLP

By:

/s/ Yvan-Claude Pierre

Yvan-Claude Pierre

GRAPHIC

Filename: tm2615979d1_ex5-1img01.jpg · Sequence: 6

Binary file (2684 bytes)

Download tm2615979d1_ex5-1img01.jpg

XML — IDEA: XBRL DOCUMENT

XML

Filename: R1.htm · Sequence: 8

v3.26.1

Cover

May 29, 2026

Cover [Abstract]

Document Type

8-K

Amendment Flag

false

Document Period End Date

May 29, 2026

Entity File Number

001-37759

Entity Registrant Name

Outlook Therapeutics,

Inc.

Entity Central Index Key

0001649989

Entity Tax Identification Number

38-3982704

Entity Incorporation, State or Country Code

Entity Address, Address Line One

111

S. Wood Avenue,

Entity Address, Address Line Two

Unit

#100

Entity Address, City or Town

Iselin

Entity Address, State or Province

Entity Address, Postal Zip Code

08830

City Area Code

609

Local Phone Number

619-3990

Written Communications

false

Soliciting Material

false

Pre-commencement Tender Offer

false

Pre-commencement Issuer Tender Offer

false

Title of 12(b) Security

Common Stock

Trading Symbol

OTLK

Security Exchange Name

NASDAQ

Entity Emerging Growth Company

false

- Definition

Boolean flag that is true when the XBRL content amends previously-filed or accepted submission.

+ References

No definition available.

+ Details

Name:

dei_AmendmentFlag

Namespace Prefix:

dei_

Data Type:

xbrli:booleanItemType

Balance Type:

Period Type:

duration

- Definition

Area code of city

+ References

No definition available.

+ Details

Name:

dei_CityAreaCode

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

Cover page.

+ References

No definition available.

+ Details

Name:

dei_CoverAbstract

Namespace Prefix:

dei_

Data Type:

xbrli:stringItemType

Balance Type:

Period Type:

duration

- Definition

For the EDGAR submission types of Form 8-K: the date of the report, the date of the earliest event reported; for the EDGAR submission types of Form N-1A: the filing date; for all other submission types: the end of the reporting or transition period. The format of the date is YYYY-MM-DD.

+ References

No definition available.

+ Details

Name:

dei_DocumentPeriodEndDate

Namespace Prefix:

dei_

Data Type:

xbrli:dateItemType

Balance Type:

Period Type:

duration

- Definition

The type of document being provided (such as 10-K, 10-Q, 485BPOS, etc). The document type is limited to the same value as the supporting SEC submission type, or the word 'Other'.

+ References

No definition available.

+ Details

Name:

dei_DocumentType

Namespace Prefix:

dei_

Data Type:

dei:submissionTypeItemType

Balance Type:

Period Type:

duration

- Definition

Address Line 1 such as Attn, Building Name, Street Name

+ References

No definition available.

+ Details

Name:

dei_EntityAddressAddressLine1

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

Address Line 2 such as Street or Suite number

+ References

No definition available.

+ Details

Name:

dei_EntityAddressAddressLine2

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

Name of the City or Town

+ References

No definition available.

+ Details

Name:

dei_EntityAddressCityOrTown

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

Code for the postal or zip code

+ References

No definition available.

+ Details

Name:

dei_EntityAddressPostalZipCode

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

Name of the state or province.

+ References

No definition available.

+ Details

Name:

dei_EntityAddressStateOrProvince

Namespace Prefix:

dei_

Data Type:

dei:stateOrProvinceItemType

Balance Type:

Period Type:

duration

- Definition

A unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection b-2

+ Details

Name:

dei_EntityCentralIndexKey

Namespace Prefix:

dei_

Data Type:

dei:centralIndexKeyItemType

Balance Type:

Period Type:

duration

- Definition

Indicate if registrant meets the emerging growth company criteria.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection b-2

+ Details

Name:

dei_EntityEmergingGrowthCompany

Namespace Prefix:

dei_

Data Type:

xbrli:booleanItemType

Balance Type:

Period Type:

duration

- Definition

Commission file number. The field allows up to 17 characters. The prefix may contain 1-3 digits, the sequence number may contain 1-8 digits, the optional suffix may contain 1-4 characters, and the fields are separated with a hyphen.

+ References

No definition available.

+ Details

Name:

dei_EntityFileNumber

Namespace Prefix:

dei_

Data Type:

dei:fileNumberItemType

Balance Type:

Period Type:

duration

- Definition

Two-character EDGAR code representing the state or country of incorporation.

+ References

No definition available.

+ Details

Name:

dei_EntityIncorporationStateCountryCode

Namespace Prefix:

dei_

Data Type:

dei:edgarStateCountryItemType

Balance Type:

Period Type:

duration

- Definition

The exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection b-2

+ Details

Name:

dei_EntityRegistrantName

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

The Tax Identification Number (TIN), also known as an Employer Identification Number (EIN), is a unique 9-digit value assigned by the IRS.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection b-2

+ Details

Name:

dei_EntityTaxIdentificationNumber

Namespace Prefix:

dei_

Data Type:

dei:employerIdItemType

Balance Type:

Period Type:

duration

- Definition

Local phone number for entity.

+ References

No definition available.

+ Details

Name:

dei_LocalPhoneNumber

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 13e

-Subsection 4c

+ Details

Name:

dei_PreCommencementIssuerTenderOffer

Namespace Prefix:

dei_

Data Type:

xbrli:booleanItemType

Balance Type:

Period Type:

duration

- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 14d

-Subsection 2b

+ Details

Name:

dei_PreCommencementTenderOffer

Namespace Prefix:

dei_

Data Type:

xbrli:booleanItemType

Balance Type:

Period Type:

duration

- Definition

Title of a 12(b) registered security.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection b

+ Details

Name:

dei_Security12bTitle

Namespace Prefix:

dei_

Data Type:

dei:securityTitleItemType

Balance Type:

Period Type:

duration

- Definition

Name of the Exchange on which a security is registered.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection d1-1

+ Details

Name:

dei_SecurityExchangeName

Namespace Prefix:

dei_

Data Type:

dei:edgarExchangeCodeItemType

Balance Type:

Period Type:

duration

- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as soliciting material pursuant to Rule 14a-12 under the Exchange Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 14a

-Subsection 12

+ Details

Name:

dei_SolicitingMaterial

Namespace Prefix:

dei_

Data Type:

xbrli:booleanItemType

Balance Type:

Period Type:

duration

- Definition

Trading symbol of an instrument as listed on an exchange.

+ References

No definition available.

+ Details

Name:

dei_TradingSymbol

Namespace Prefix:

dei_

Data Type:

dei:tradingSymbolItemType

Balance Type:

Period Type:

duration

- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as written communications pursuant to Rule 425 under the Securities Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Securities Act

-Number 230

-Section 425

+ Details

Name:

dei_WrittenCommunications

Namespace Prefix:

dei_

Data Type:

xbrli:booleanItemType

Balance Type:

Period Type:

duration