Perspective Therapeutics holder sells 42,129 shares

A 10% owner associated with Lantheus sold 42,129 CATX shares but continues to hold over 11.5 million shares.

Rhea-AI Filing Summary

Perspective Therapeutics, Inc. (CATX) reported that significant stockholder Lantheus Alpha Therapy, LLC sold 42,129 shares of CATX common stock on September 2, 2026 in an open-market or private transaction at a weighted average price of $3.1147 per share, with individual trade prices ranging from $3.025 to $3.235. After this sale, Lantheus Alpha Therapy, LLC directly holds 11,521,296 CATX shares, and Lantheus Holdings, Inc., as its indirect parent, may be deemed to have indirect beneficial ownership of those shares under SEC rules.

Insider Trade Summary

Net Seller: 42,129 shares

Net Sell 1 txn

Insider Lantheus Alpha Therapy, LLC, Lantheus Holdings, Inc.

Role 10% Owner | 10% Owner

Sold 42,129 shs ($131K)

Type	Security	Shares	Price	Value
Sale	Common Stock F1, F2	42,129	$3.1147	$131K

Holdings After Transaction: Common Stock — 11,521,296 shares (Direct)

Footnotes (2)

1. F1. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $3.025 to $3.235, inclusive. The reporting person undertakes to provide to Perspective Therapeutics, Inc. ("CATX"), any security holder of CATX or the staff of the Securities and Exchange Commission ("SEC"), upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (1) to this Form 4.
2. F2. Represents securities directly held by Lantheus Alpha Therapy, LLC ("Lantheus"), a wholly owned indirect subsidiary of Lantheus Holdings, Inc. ("Lantheus Holdings"). Under SEC rules and regulations, Lantheus Holdings may be deemed to have indirect beneficial ownership of the shares held by Lantheus, which has direct beneficial ownership.

Key Figures

Shares sold: 42,129 shares Weighted average sale price: $3.1147 per share Post-transaction holdings: 11,521,296 shares +2 more

5 metrics

Shares sold 42,129 shares Common stock sale on September 2, 2026

Weighted average sale price $3.1147 per share Average of multiple sale transactions ranging from $3.025 to $3.235

Post-transaction holdings 11,521,296 shares Shares of CATX common stock directly held by Lantheus Alpha Therapy, LLC after the sale

Sale price range $3.025–$3.235 per share Price range of the multiple transactions included in the reported sale

Net shares sold 42,129 shares Net change in beneficial ownership reported in the transaction summary

Key Terms

weighted average price, indirect beneficial ownership, ten percent owner, open market or private transaction

4 terms

weighted average price financial

"The price reported in Column 4 is a weighted average price."

Weighted average price is the average price of a security where each trade or component is counted according to its size, so bigger trades pull the average more than smaller ones. Think of it like calculating the average cost of a grocery haul where items you bought more of have greater influence on the final per-item cost. Investors use it to understand the true average price paid or received, judge execution quality, and compare trading performance against market movement.

indirect beneficial ownership financial

"Lantheus Holdings may be deemed to have indirect beneficial ownership of the shares"

ten percent owner regulatory

"The reporting persons are each identified as a ten percent owner of CATX"

open market or private transaction financial

"Sale in open market or private transaction"

FAQ

What insider transaction did CATX report for Lantheus Alpha Therapy, LLC?

CATX reported that Lantheus Alpha Therapy, LLC sold 42,129 shares of Perspective Therapeutics common stock on September 2, 2026, in a sale classified as an open-market or private transaction, and continued to hold a large remaining position afterward.

At what price were the 42,129 CATX shares sold?

The 42,129 CATX shares were sold at a weighted average price of $3.1147 per share. The filing states that the shares were sold in multiple transactions at prices ranging from $3.025 to $3.235 per share, inclusive.

How many CATX shares does Lantheus Alpha Therapy, LLC hold after this sale?

After the reported sale, Lantheus Alpha Therapy, LLC directly holds 11,521,296 shares of Perspective Therapeutics common stock. This post-transaction holding is disclosed as the amount beneficially owned following the transaction.

What is the relationship between Lantheus Alpha Therapy, LLC and Lantheus Holdings, Inc. in the CATX filing?

The filing states that the reported CATX shares are directly held by Lantheus Alpha Therapy, LLC, which is a wholly owned indirect subsidiary of Lantheus Holdings, Inc. Under SEC rules, Lantheus Holdings may be deemed to have indirect beneficial ownership of those shares.

Was the CATX insider sale made under a Rule 10b5-1 trading plan?

The Form 4 indicates the Rule 10b5-1 checkbox is not marked as affirmative, and the footnotes do not reference any trading plan, so no Rule 10b5-1 plan is reported in connection with this sale.

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Available on EDGAR 09/04/2026 - 05:01 PM Accepted by SEC EDGAR 09/04/2026 - 05:00 PM Learn about SEC filing dates

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Lantheus Alpha Therapy, LLC

(Last) (First) (Middle)

C/O LANTHEUS HOLDINGS, INC.

201 BURLINGTON ROAD, SOUTH BUILDING

(Street)

BEDFORD MASSACHUSETTS 01730

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Perspective Therapeutics, Inc. [ CATX ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
09/02/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

	Form filed by One Reporting Person
X	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	09/02/2026		S		42,129	D	$3.1147(1)	11,521,296	D(2)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

1. Name and Address of Reporting Person^*

Lantheus Alpha Therapy, LLC

(Last) (First) (Middle)

C/O LANTHEUS HOLDINGS, INC.

201 BURLINGTON ROAD, SOUTH BUILDING

(Street)

BEDFORD MASSACHUSETTS 01730

(City) (State) (Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

1. Name and Address of Reporting Person^*

Lantheus Holdings, Inc.

(Last) (First) (Middle)

331 TREBLE COVE ROAD

(Street)

NORTH BILLERICA MASSACHUSETTS 01862

(City) (State) (Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

Explanation of Responses:

1. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $3.025 to $3.235, inclusive. The reporting person undertakes to provide to Perspective Therapeutics, Inc. ("CATX"), any security holder of CATX or the staff of the Securities and Exchange Commission ("SEC"), upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (1) to this Form 4.

2. Represents securities directly held by Lantheus Alpha Therapy, LLC ("Lantheus"), a wholly owned indirect subsidiary of Lantheus Holdings, Inc. ("Lantheus Holdings"). Under SEC rules and regulations, Lantheus Holdings may be deemed to have indirect beneficial ownership of the shares held by Lantheus, which has direct beneficial ownership.

	/s/ Eric M. Green, Assistant Corporate Secretary of Lantheus Holdings	09/04/2026
	/s/ Eric M. Green, Assistant Corporate Secretary of Lantheus	09/04/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)