Medifast (MED): Citadel entities and Kenneth Griffin disclose sub‑5% ownership stake

Rhea-AI Filing Summary

Medifast Inc. received an amended Schedule 13G from a group of Citadel-related entities and Kenneth Griffin regarding ownership of its common stock. The reporting persons, including Citadel Securities LLC, Citadel Securities Group LP, Citadel Advisors LLC and related entities, plus Mr. Griffin, report beneficial ownership well below 5% of Medifast’s shares.

Citing 11,119,115 Shares outstanding as of April 27, 2026, Citadel Securities LLC may be deemed to beneficially own 233,401 Shares (2.1%), certain Citadel Securities Group entities 236,447 Shares (2.1%), certain Citadel Advisors entities 53,304 Shares (0.5%), and Kenneth Griffin 289,751 Shares (2.6%), all with shared and no sole voting or dispositive power. The filing confirms ownership of 5 percent or less of the class.

Key Figures

Shares outstanding baseline: 11,119,115 Shares Citadel Securities LLC beneficial ownership: 233,401 Shares (2.1%) Citadel Securities Group LP / GP LLC ownership: 236,447 Shares (2.1%) +4 more

7 metrics

Shares outstanding baseline 11,119,115 Shares Shares outstanding as of April 27, 2026 used for ownership percentages

Citadel Securities LLC beneficial ownership 233,401 Shares (2.1%) Medifast common stock that Citadel Securities LLC may be deemed to beneficially own

Citadel Securities Group LP / GP LLC ownership 236,447 Shares (2.1%) Medifast Shares each of Citadel Securities Group LP and Citadel Securities GP LLC may be deemed to own

Citadel Advisors complex ownership 53,304 Shares (0.5%) Medifast Shares each of Citadel Advisors LLC, Citadel Advisors Holdings LP and Citadel GP LLC may be deemed to own

Kenneth Griffin beneficial ownership 289,751 Shares (2.6%) Medifast common stock Kenneth Griffin may be deemed to beneficially own

Sole voting power 0 Shares All reporting persons disclose zero sole power to vote Medifast Shares

Shared voting power (Griffin) 289,751 Shares Shares over which Kenneth Griffin has shared power to vote and dispose

Key Terms

beneficially own, shared voting power, shared dispositive power, Schedule 13G, +1 more

5 terms

beneficially own financial

"may be deemed to beneficially own 289,751 Shares"

Beneficially own means having the economic rights and risks of a security—such as the right to receive dividends, sell the shares, or profit from price changes—whether or not your name appears on the official share register. Think of it like renting a car: you use it and reap the benefits even if the title lists someone else. Investors care because beneficial ownership determines who truly controls value, must be disclosed under securities rules, and can signal potential influence or trading activity that affects a stock’s price.

shared voting power financial

"Shared power to vote or to direct the vote: 289,751"

Shared voting power occurs when two or more parties jointly have the right to vote or decide how a block of company shares is cast, like co-owners who must agree before moving a piece of furniture. Investors care because who controls voting rights affects board elections, major corporate decisions and takeover outcomes, and shared control can alter regulatory disclosures and the practical influence any holder has over a company’s direction and value.

shared dispositive power financial

"Shared power to dispose or to direct the disposition of: 289,751"

Schedule 13G regulatory

"being jointly filed by Citadel Securities GP LLC ... This Schedule 13G is"

A Schedule 13G is a formal document that investors file with the government when they acquire a large ownership stake in a company, usually for investment purposes rather than control. It helps keep the public informed about who owns significant parts of a company's shares, which can influence how the company is managed and how investors make decisions. Filing this schedule is important for transparency and understanding the ownership landscape of publicly traded companies.

attorney-in-fact regulatory

"Seth Levy is signing on behalf of Kenneth Griffin as attorney-in-fact"

An attorney-in-fact is the person or entity given legal authority through a power of attorney to act on behalf of another for specific tasks, such as signing documents, voting shares, or handling transactions. For investors, this matters because it lets a trusted representative make timely decisions or complete paperwork when the owner cannot, much like handing keys to someone to run errands on your behalf—so checks on scope and limits of that authority are important.

FAQ

What Medifast (MED) ownership is reported by Citadel Securities LLC in this Schedule 13G/A?

Citadel Securities LLC may be deemed to beneficially own 233,401 Medifast Shares, representing 2.1% of the Shares outstanding, based on 11,119,115 Shares outstanding as of April 27, 2026, with only shared voting and dispositive power.

How many Medifast (MED) shares does Kenneth Griffin beneficially own according to this filing?

Kenneth Griffin may be deemed to beneficially own 289,751 Medifast Shares, equal to 2.6% of the outstanding Shares. He has 0 sole voting or dispositive power and 289,751 Shares of shared voting and shared dispositive power.

Do the Citadel-related reporting persons own more than 5% of Medifast (MED)?

No, each reporting person states ownership of 5 percent or less of Medifast’s common stock. Percentages range from 0.5% for certain Citadel Advisors entities to 2.6% for Kenneth Griffin, all calculated on 11,119,115 Shares outstanding.

What Medifast (MED) share count was used to calculate the ownership percentages?

All reported ownership percentages are based on 11,119,115 Medifast Shares outstanding as of April 27, 2026, as referenced from Medifast’s Form 10-Q filed on May 4, 2026, which the reporting group cites in the ownership calculations.

What type of voting and dispositive power do the Citadel entities and Kenneth Griffin report over Medifast (MED) shares?

The reporting persons disclose no sole voting or dispositive power (0 Shares). All Medifast positions are held with shared voting power and shared dispositive power, matching each entity’s reported beneficially owned share count.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 08/14/2026 - 04:22 PM Accepted by SEC EDGAR 08/14/2026 - 04:15 PM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 1)

MEDIFAST INC

(Name of Issuer)

Common Stock, par value $0.001 per share (the "Shares")

(Title of Class of Securities)

58470H101

(CUSIP Number)

06/30/2026

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

schemaVersion:

SCHEDULE 13G

CUSIP Number(s): 58470H101

1

Names of Reporting Persons

Citadel Securities GP LLC

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 236,447.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 236,447.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

236,447.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

2.1 %

12

Type of Reporting Person (See Instructions)

HC, OO

Comment for Type of Reporting Person: The percentages reported in this Schedule 13G are based upon 11,119,115 Shares outstanding as of April 27, 2026 (according to the issuer's Form 10-Q as filed with the Securities and Exchange Commission on May 4, 2026).

SCHEDULE 13G

CUSIP Number(s): 58470H101

1

Names of Reporting Persons

Citadel Securities LLC

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 233,401.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 233,401.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

233,401.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

2.1 %

12

Type of Reporting Person (See Instructions)

BD, OO

SCHEDULE 13G

CUSIP Number(s): 58470H101

1

Names of Reporting Persons

Citadel Securities Group LP

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 236,447.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 236,447.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

236,447.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

2.1 %

12

Type of Reporting Person (See Instructions)

HC, PN

SCHEDULE 13G

CUSIP Number(s): 58470H101

1

Names of Reporting Persons

Citadel Advisors LLC

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 53,304.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 53,304.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

53,304.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

0.5 %

12

Type of Reporting Person (See Instructions)

IA, HC, OO

SCHEDULE 13G

CUSIP Number(s): 58470H101

1

Names of Reporting Persons

Citadel Advisors Holdings LP

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 53,304.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 53,304.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

53,304.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

0.5 %

12

Type of Reporting Person (See Instructions)

HC, PN

SCHEDULE 13G

CUSIP Number(s): 58470H101

1

Names of Reporting Persons

Citadel GP LLC

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 53,304.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 53,304.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

53,304.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

0.5 %

12

Type of Reporting Person (See Instructions)

HC, OO

SCHEDULE 13G

CUSIP Number(s): 58470H101

1

Names of Reporting Persons

Kenneth Griffin

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 289,751.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 289,751.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

289,751.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

2.6 %

12

Type of Reporting Person (See Instructions)

HC, IN

SCHEDULE 13G

Item 1.
(a)	Name of issuer: MEDIFAST INC
(b)	Address of issuer's principal executive offices: 1501 S. Clinton Street, Suite 500, Baltimore, MD 21224
Item 2.
(a)	Name of person filing: This Schedule 13G is being jointly filed by Citadel Securities GP LLC ("CSGP"), Citadel Securities LLC ("Citadel Securities"), Citadel Securities Group LP ("CALC4"), Citadel Advisors LLC ("Citadel Advisors"), Citadel Advisors Holdings LP ("CAH"), Citadel GP LLC ("CGP"), and Mr. Kenneth Griffin (collectively with CSGP, Citadel Securities, CALC4, Citadel Advisors, CAH, and CGP, the "Reporting Persons") with respect to the Shares of the above-named issuer held of record by Citadel Quantitative Strategies Master Fund Ltd., a Cayman Islands limited company ("CQ"), Citadel Securities and Citadel Securities Principal Strategies LLC, a Delaware limited liability company ("CSP"). Such Shares may include other instruments exercisable for or convertible into Shares. CALC4 is the non-member manager of Citadel Securities and CSP. CSGP is the general partner of CALC4. Citadel Advisors is the portfolio manager for CQ. CAH is the sole member of Citadel Advisors. CGP is the general partner of CAH. Mr. Griffin is the President and Chief Executive Officer of CGP, and owns a controlling interest in CGP and CSGP.
(b)	Address or principal business office or, if none, residence: The address of each of the Reporting Persons is 830 Brickell Plaza, Miami, Florida 33131.
(c)	Citizenship: Each of CSGP, Citadel Securities, Citadel Advisors, and CGP is organized as a limited liability company under the laws of the State of Delaware. Each of CALC4 and CAH is organized as a limited partnership under the laws of the State of Delaware. Mr. Griffin is a U.S. citizen.
(d)	Title of class of securities: Common Stock, par value $0.001 per share (the "Shares")
(e)	CUSIP No.: 58470H101
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: 1. Citadel Securities LLC may be deemed to beneficially own 233,401 Shares. 2. Each of Citadel Securities Group LP and Citadel Securities GP LLC may be deemed to beneficially own 236,447 Shares. 3. Each of Citadel Advisors LLC, Citadel Advisors Holdings LP and Citadel GP LLC may be deemed to beneficially own 53,304 Shares. 4. Mr. Griffin may be deemed to beneficially own 289,751 Shares.
(b)	Percent of class: 1. The number of Shares that Citadel Securities LLC may be deemed to beneficially own constitutes 2.1% of the Shares outstanding. 2. The number of Shares that each of Citadel Securities Group LP and Citadel Securities GP LLC may be deemed to beneficially own constitutes 2.1% of the Shares outstanding. 3. The number of Shares that each of Citadel Advisors LLC, Citadel Advisors Holdings LP and Citadel GP LLC may be deemed to beneficially own constitutes 0.5% of the Shares outstanding. 4. The number of Shares that Mr. Griffin may be deemed to beneficially own constitutes 2.6% of the Shares outstanding.
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 1. Citadel Securities LLC: 0 2. Each of Citadel Securities Group LP and Citadel Securities GP LLC: 0 3. Each of Citadel Advisors LLC, Citadel Advisors Holdings LP and Citadel GP LLC: 0 4. Mr. Griffin: 0
	(ii) Shared power to vote or to direct the vote: 1. Citadel Securities LLC: 233,401 2. Each of Citadel Securities Group LP and Citadel Securities GP LLC: 236,447 3. Each of Citadel Advisors LLC, Citadel Advisors Holdings LP and Citadel GP LLC: 53,304 4. Mr. Griffin: 289,751
	(iii) Sole power to dispose or to direct the disposition of: 1. Citadel Securities LLC: 0 2. Each of Citadel Securities Group LP and Citadel Securities GP LLC: 0 3. Each of Citadel Advisors LLC, Citadel Advisors Holdings LP and Citadel GP LLC: 0 4. Mr. Griffin: 0
	(iv) Shared power to dispose or to direct the disposition of: 1. Citadel Securities LLC: 233,401 2. Each of Citadel Securities Group LP and Citadel Securities GP LLC: 236,447 3. Each of Citadel Advisors LLC, Citadel Advisors Holdings LP and Citadel GP LLC: 53,304 4. Mr. Griffin: 289,751
Item 5.	Ownership of 5 Percent or Less of a Class.
	Ownership of 5 percent or less of a class
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	Not Applicable
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Citadel Securities GP LLC

Signature:	/s/ Seth Levy
Name/Title:	Seth Levy, Authorized Signatory
Date:	08/14/2026

Citadel Securities LLC

Signature:	/s/ Seth Levy
Name/Title:	Seth Levy, Authorized Signatory
Date:	08/14/2026

Citadel Securities Group LP

Signature:	/s/ Seth Levy
Name/Title:	Seth Levy, Authorized Signatory
Date:	08/14/2026

Citadel Advisors LLC

Signature:	/s/ Seth Levy
Name/Title:	Seth Levy, Authorized Signatory
Date:	08/14/2026

Citadel Advisors Holdings LP

Signature:	/s/ Seth Levy
Name/Title:	Seth Levy, Authorized Signatory
Date:	08/14/2026

Citadel GP LLC

Signature:	/s/ Seth Levy
Name/Title:	Seth Levy, Authorized Signatory
Date:	08/14/2026

Kenneth Griffin

Signature:	/s/ Seth Levy
Name/Title:	Seth Levy, attorney-in-fact*
Date:	08/14/2026

Comments accompanying signature: * Seth Levy is signing on behalf of Kenneth Griffin as attorney-in-fact pursuant to a power of attorney previously filed with the Securities and Exchange Commission, and hereby incorporated by reference herein. The power of attorney was filed as an attachment to a filing by Citadel Advisors LLC on Schedule 13G for Allakos Inc. on October 13, 2023.