NextNav (NN) investor Subin, Milfam entities fall under 5% ownership

Rhea-AI Filing Summary

NextNav Inc. shareholder Neil S. Subin and affiliated entities have filed an amended Schedule 13D indicating they are no longer beneficial owners of more than five percent of the company’s common stock. Subin now reports beneficial ownership of 3,447,328 shares, representing 2.5% of the common stock, including direct holdings, shares held through Sufam Advisors Corp., warrants and convertible notes-related shares. MILFAM CI LLC Spartacus reports 5,488,884 shares, or 3.9%, including common stock and warrants, while MILFAM CI Management LLC reports no beneficial ownership. A Portfolio Management Agreement dated May 22, 2026, appoints Warberg Asset Management LLC as investment advisor to CI Spartacus with sole discretionary trading authority, which results in Subin and CI Management no longer being deemed beneficial owners of the CI Spartacus holdings.

Insights

Equity ownership & governance analyst

Large NextNav holder and related entities fall below 5% ownership.

The amendment shows Neil S. Subin now beneficially owns 3,447,328 NextNav shares, or 2.5% of the common stock, while MILFAM CI LLC Spartacus holds 5,488,884 shares, or 3.9%. Both stakes are below the 5% Schedule 13D reporting threshold.

Subin’s reported stake includes common shares, 5.00% Senior Secured Convertible Notes due 2028 (convertible into 501,592 shares), and 250,000 warrant shares via entities he manages. CI Spartacus’ position combines common shares and 3,539,977 warrant shares.

On May 22, 2026, CI Spartacus entered a Portfolio Management Agreement appointing Warberg Asset Management LLC with sole discretionary trading authority. Because of this, Subin and MILFAM CI Management LLC are no longer deemed beneficial owners of CI Spartacus’ holdings, making this amendment an exit filing for their prior >5% status.

Key Figures

Subin beneficial ownership: 3,447,328 shares (2.5%) CI Spartacus beneficial ownership: 5,488,884 shares (3.9%) Shares outstanding: 136,436,939 shares +5 more

8 metrics

Subin beneficial ownership 3,447,328 shares (2.5%) NextNav common stock as of May 11, 2026 basis

CI Spartacus beneficial ownership 5,488,884 shares (3.9%) NextNav common stock as of May 11, 2026 basis

Shares outstanding 136,436,939 shares NextNav common stock outstanding as of May 11, 2026

Milfam Investments warrants 250,000 warrants Exercisable into 250,000 NextNav common shares

CI Spartacus warrants 3,539,977 warrants Exercisable into 3,539,977 NextNav common shares

Note Shares 501,592 shares From 5.00% Senior Secured Convertible Notes due 2028 held by Persian Road I, LP

Convertible note rate 5.00% Senior Secured Convertible Notes due 2028

CI Management ownership 0 shares (0.0%) Reported beneficial ownership of NextNav common stock

Key Terms

beneficial ownership, Schedule 13D, Rule 13d-3(d)(1), Portfolio Management Agreement, +1 more

5 terms

beneficial ownership financial

"has ceased to be the beneficial owner of more than five percent of Common Stock"

Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.

Schedule 13D regulatory

"amends and supplements the originally filed by the Reporting Persons with the SEC on August 19, 2022"

A Schedule 13D is a legal document that investors file with regulators when they buy a large enough stake in a company to potentially influence its management or decisions. It provides details about the investor’s intention, ownership stake, and plans, helping other investors understand who is gaining control and what their motives might be.

Rule 13d-3(d)(1) regulatory

"based upon the deemed to be outstanding shares of Common Stock pursuant to Rule 13d-3(d)(1)"

Portfolio Management Agreement financial

"entered into a Portfolio Management Agreement (the "PMA") with Warberg Asset Management LLC"

Senior Secured Convertible Notes financial

"5.00% Senior Secured Convertible Notes due 2028, held by Persian Road I, LP"

A senior secured convertible note is a loan a company issues that sits near the top of its repayment order (senior), is backed by specific assets as collateral (secured), and can be swapped into company shares later (convertible). For investors this matters because it combines lower risk of repayment and legal protection from the collateral with the upside of converting into equity—so it affects both the safety of debt holders and potential dilution for shareholders.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 1)

NEXTNAV INC.

(Name of Issuer)

Common Stock, par value $0.0001 per share

(Title of Class of Securities)

65345N106

(CUSIP Number)

Neil S. Subin
2366 SE Ocean Blvd, Suite 400,
Stuart, FL, 34996
(561) 287-5399

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

05/22/2026

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.

The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

schemaVersion:

SCHEDULE 13D

CUSIP Number(s): 65345N106

1

Name of reporting person

SUBIN NEIL S

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF, OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 180,523.00
8	Shared Voting Power 3,266,805.00
9	Sole Dispositive Power 180,523.00
10	Shared Dispositive Power 3,266,805.00

11

Aggregate amount beneficially owned by each reporting person

3,447,328.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

2.5 %

14

Type of Reporting Person (See Instructions)

IN

Comment for Type of Reporting Person:

Note to Rows 7, 9 and 11: Includes 11,631 shares of common stock, par value $0.0001 per share ("Common Stock"), of NextNav Inc. (the "Issuer") held by Sufam Advisors Corp. ("SAC"), which is 100% owned by SF Nevis Investco LLC ("Nevis"). Mr. Subin manages Nevis. Mr. Subin disclaims any beneficial ownership of the securities owned by SAC other than to the extent of any pecuniary interest he may have therein, directly or indirectly. Note to Rows 8, 10 and 11: Represents 2,515,213 shares of Common Stock held by MILFAM Investments LLC ("Milfam Investments") and 250,000 warrants held by Milfam Investments that are exercisable for 250,000 shares of Common Stock (the "Warrant Shares"). Mr. Subin is the President and Manager of MILFAM LLC, which serves as manager of Milfam Investments, consequently, he may be deemed to share beneficial ownership of the shares of Common Stock held by Milfam Investments. Also, represents 501,592 shares of Common Stock (the "Note Shares"), which are convertible from 5.00% Senior Secured Convertible Notes due 2028, held by Persian Road I, LP ("Persian Road"). Mr. Subin manages Persian Road. Mr. Subin disclaims any beneficial ownership of the reported shares other than to the extent of any pecuniary interest he may have therein, directly or indirectly. Note to Row 13: The percentages reported in this Amendment No. 1 to Schedule 13D (this "Amendment") are based upon the deemed to be outstanding shares of Common Stock pursuant to Rule 13d-3(d)(1) of the Securities Exchange Act of 1934, as amended ("Rule 13d-3(d)(1)"), which includes (i) 136,436,939 shares of Common Stock outstanding as of May 11, 2026 (according to the Issuer's Quarterly Report on Form 10-Q filed with the U.S. Securities and Exchange Commission on May 14, 2026 (the "Form 10-Q") plus (ii) the Warrant Shares, plus (iii) the Note Shares, although the Warrant Shares and Note Shares are not deemed to be outstanding for the purpose of computing the percentage of the class owned by any other person besides Mr. Subin. Mr. Subin has ceased to be the beneficial owner of more than five percent of Common Stock and, as such, this Amendment constitutes an exit filing for Mr. Subin.

SCHEDULE 13D

CUSIP Number(s): 65345N106

1

Name of reporting person

Milfam CI LLC Spartacus

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

WC

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 5,488,884.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 5,488,884.00

11

Aggregate amount beneficially owned by each reporting person

5,488,884.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

3.9 %

14

Type of Reporting Person (See Instructions)

OO

Comment for Type of Reporting Person:

Note to Rows 8, 10 and 11: Represents 1,948,907 shares of Common Stock held by MILFAM CI LLC SPARTACUS ("CI Spartacus") and 3,539,977 warrants held by CI Spartacus that are exercisable for 3,539,977 shares of Common Stock ("CI Spartacus Warrant Shares"). Note to Row 13: The percentages reported in this Amendment are based upon the deemed to be outstanding shares of Common Stock pursuant to Rule 13d-3(d)(1), which includes (i) 136,436,939 shares of Common Stock outstanding as of May 11, 2026 (according to the Form 10-Q) plus (ii) the CI Spartacus Warrant Shares, although the CI Spartacus Warrant Shares are not deemed to be outstanding for the purpose of computing the percentage of the class owned by any other person besides CI Spartacus. CI Spartacus has ceased to be the beneficial owner of more than five percent of Common Stock and, as such, this Amendment constitutes an exit filing for CI Spartacus.

SCHEDULE 13D

CUSIP Number(s): 65345N106

1

Name of reporting person

MILFAM CI Management LLC

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF, OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 0.00

11

Aggregate amount beneficially owned by each reporting person

0.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

0.0 %

14

Type of Reporting Person (See Instructions)

OO

Comment for Type of Reporting Person:

Note to Row 13: MILFAM CI Management LLC ("CI Management") has ceased to be the beneficial owner of more than five percent of Common Stock and, as such, this Amendment constitutes an exit filing for CI Management.

SCHEDULE 13D

Item 1.	Security and Issuer
(a)	Title of Class of Securities: Common Stock, par value $0.0001 per share
(b)	Name of Issuer: NEXTNAV INC.
(c)	Address of Issuer's Principal Executive Offices: 11911 Freedom Dr., Suite 200, Reston, VIRGINIA , 20190.
Item 1 Comment: This Amendment is filed with the SEC on behalf of (i) Mr. Subin, (ii) CI Spartacus, and (iii) CI Management (each person and entity named in items (i) through (iii), collectively, the "Reporting Persons") relating to Common Stock. This Amendment amends and supplements the Schedule 13D originally filed by the Reporting Persons with the SEC on August 19, 2022 (the "Schedule 13D"). Except as specifically provided herein, this Amendment does not modify any of the information previously reported in the Schedule 13D. Capitalized terms used but not defined in this Amendment shall have the same meanings ascribed to them in the Schedule 13D.
Item 5.	Interest in Securities of the Issuer
(a)	See rows (11) and (13) of the cover pages to this Amendment for the aggregate number of shares of Common Stock and percentages of the shares of Common Stock beneficially owned by each Reporting Person. The percentage reported in this Amendment is based upon 136,439,939 shares of Common Stock outstanding as of May 11, 2026 (according to the Form 10-Q).
(b)	See rows (7) through (10) of the cover pages to this Amendment for the number of shares of Common Stock as to which each Reporting Person has the sole or shared power to vote or direct the vote and sole or shared power to dispose or to direct the disposition.
(c)	The following transactions were effected in the sixty days prior to the date of this Amendment involving the Reporting Persons: N/A
(d)	N/A
(e)	May 22, 2026
Item 6.	Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer
	On May 22, 2026, CI Spartacus entered into a Portfolio Management Agreement (the "PMA") with Warberg Asset Management LLC (the "Portfolio Manager"), pursuant to which CI Spartacus appointed the Portfolio Manager as its investment advisor with sole and exclusive discretionary trading authority over securities held by CI Spartacus. As a result of the PMA, neither CI Management nor Mr. Subin, through his ownership and control of CI Management, retains beneficial ownership of the securities held by CI Spartacus, and each Reporting Person has accordingly ceased to be the beneficial owner of more than five percent of the Common Stock.
Item 7.	Material to be Filed as Exhibits.
	Exhibit 1 - Portfolio Management Agreement, dated May 22, 2026, by and between Warberg Asset Management LLC and MILFAM CI LLC SPARTACUS. (Schedules and exhibits have been omitted as they are not material. They will be furnished supplementally to the SEC upon request.)

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.

SUBIN NEIL S

Signature:	/s/ Neil S. Subin
Name/Title:	Neil S. Subin
Date:	05/22/2026

Milfam CI LLC Spartacus

Signature:	/s/ Neil S. Subin
Name/Title:	Neil S. Subin/Sole Member of Milfam CI Management LLC, Manager of Milfam CI LLC Spartacus
Date:	05/22/2026

MILFAM CI Management LLC

Signature:	/s/ Neil S. Subin
Name/Title:	Neil S. Subin/Sole Member
Date:	05/22/2026

FAQ

What change in ownership does this Schedule 13D/A report for NextNav (NN)?

The filing reports that Neil S. Subin and related entities have each fallen below five percent beneficial ownership of NextNav common stock. Their stakes, once reportable as large holders, are now 2.5% for Subin, 3.9% for MILFAM CI LLC Spartacus, and 0% for MILFAM CI Management LLC.

How many NextNav (NN) shares does Neil S. Subin now beneficially own?

Neil S. Subin reports beneficial ownership of 3,447,328 NextNav common shares, representing 2.5% of the class. This total includes directly held shares, shares through Sufam Advisors Corp., 250,000 warrant shares via Milfam Investments, and 501,592 shares issuable from 5.00% Senior Secured Convertible Notes due 2028.

What is MILFAM CI LLC Spartacus’s current stake in NextNav (NN)?

MILFAM CI LLC Spartacus reports beneficial ownership of 5,488,884 NextNav common shares, or 3.9% of the outstanding stock. This position consists of 1,948,907 common shares plus 3,539,977 warrants exercisable for an equal number of shares, calculated under Rule 13d-3(d)(1).

Why is this Schedule 13D/A labeled an exit filing for certain NextNav (NN) holders?

The amendment is an exit filing because the reporting persons have ceased to be beneficial owners of more than five percent of NextNav’s common stock. Each of Neil S. Subin, MILFAM CI LLC Spartacus, and MILFAM CI Management LLC now reports ownership below the five percent Schedule 13D threshold.

What is the Portfolio Management Agreement mentioned in the NextNav (NN) filing?

On May 22, 2026, MILFAM CI LLC Spartacus entered a Portfolio Management Agreement with Warberg Asset Management LLC. Under this agreement, Warberg acts as investment advisor with sole and exclusive discretionary trading authority over CI Spartacus’ securities, affecting who is deemed the beneficial owner under SEC rules.

How many NextNav (NN) shares were outstanding for the percentage calculations in this 13D/A?

The ownership percentages are based on 136,436,939 NextNav common shares outstanding as of May 11, 2026. This figure comes from the company’s Form 10-Q and is adjusted under Rule 13d-3(d)(1) to include certain warrant and convertible note shares for each reporting person’s calculation.