Form 144: Affiliate proposes sales of RARE common stock

Form 144 notice for proposed sales of Common Stock by an affiliate.

Accepted by SEC EDGAR 05/01/2026 - 04:06 PM EDT Learn about SEC filing dates

Rhea-AI Filing Summary

Form 144 notice for proposed sales of Common Stock by an affiliate. The filing lists awarded restricted stock and performance shares with grant/vesting dates and quantities: 1,743, 1,343, 939, and 658 shares tied to dates between 10/09/2024 and 03/01/2026. The filing also records multiple reported sales by Howard Horn during the prior three months, including transactions on 02/02/2026, 03/02/2026, 03/03/2026, and 04/01/2026 with per‑trade share counts of 3,061, 5,290, 3,119, 1,635, and 4,683.

Key Figures

Restricted Stock award: 1,743 shares Restricted Stock award: 1,343 shares Restricted Stock award: 939 shares +5 more

8 metrics

Restricted Stock award 1,743 shares grant/vesting date <date>10/09/2024</date>

Restricted Stock award 1,343 shares grant/vesting date <date>10/09/2025</date>

Restricted Stock award 939 shares grant/vesting date <date>03/01/2026</date>

Performance Shares award 658 shares grant/vesting date <date>03/01/2026</date>

Sale reported 4,683 shares trade date <date>04/01/2026</date>

Sale reported 5,290 shares trade date <date>03/02/2026</date>

Sale reported 3,119 shares trade date <date>03/02/2026</date>

Sale reported 3,061 shares trade date <date>02/02/2026</date>

Key Terms

Form 144, Restricted Stock, Performance Shares, Morgan Stanley Smith Barney LLC

4 terms

Form 144 regulatory

"144: Securities Sold During The Past 3 Months"

Form 144 is a document that investors must file with the government when they plan to sell a large number of shares of a company's stock. It helps ensure transparency so everyone knows how many shares are being sold and when, which can impact the stock's price.

Restricted Stock financial

"Common | 10/09/2024 | Restricted Stock"

Shares granted to an individual that carry limits on transfer or sale until certain conditions are met, such as staying with the company for a set time or hitting performance targets. Think of them as a locked gift that gradually opens; for investors they matter because they affect how many shares may enter the market later, signal management incentives and potential dilution, and reveal confidence in future company performance.

Performance Shares financial

"Common | 03/01/2026 | Performance Shares"

Performance shares are a type of company stock given to executives or employees that only become theirs if the company meets specific goals, like hitting certain profits or growth targets. They motivate leaders to work toward the company’s success, because their additional shares depend on achieving these results.

Morgan Stanley Smith Barney LLC market

"Morgan Stanley Smith Barney LLC Executive Financial Services 1 New York Plaza"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What does the RARE Form 144 disclose about proposed sales?

The Form 144 discloses proposed sales of Common Stock by an affiliate. It lists awarded restricted and performance shares of 1,743, 1,343, 939, and 658 tied to specific grant/vesting dates between 10/09/2024 and 03/01/2026.

Who reported recent sales in the RARE filing and when?

The filing lists multiple sales by Howard Horn. Reported trade dates include 02/02/2026, 03/02/2026, 03/03/2026, and 04/01/2026 with individual share counts shown in the filing.

How many shares are shown for Howard Horn's individual transactions?

Reported per‑transaction share counts in the past three months include 3,061, 5,290, 3,119, 1,635, and 4,683. Each figure is listed alongside a trade date in the filing's sales table.

Does the Form 144 list restricted or performance awards for RARE?

Yes. The filing lists awards described as Restricted Stock and Performance Shares with grant/vesting dates and specific share counts: 1,743, 1,343, 939, and 658 as shown in the securities table.

What intermediary or broker is named on the RARE filing?

The filing names Morgan Stanley Smith Barney LLC Executive Financial Services with an address at 1 New York Plaza, 8th Floor, New York, NY 10004 as the broker or clearing firm listed in the filer information.

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

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Form 144 Filer Information	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 144 NOTICE OF PROPOSED SALE OF SECURITIES PURSUANT TO RULE 144 UNDER THE SECURITIES ACT OF 1933
FORM 144

144: Filer Information

Filer CIK	0001786335
Filer CCC	XXXXXXXX
Is this a LIVE or TEST Filing?	LIVE TEST
Submission Contact Information
Name
Phone
E-Mail Address

144: Issuer Information

Name of Issuer	ULTRAGENYX PHARMACEUTICAL INC.
SEC File Number	001-36276
Address of Issuer	60 Leveroni Court Novato CALIFORNIA 94949
Phone	(415) 483-8800
Name of Person for Whose Account the Securities are To Be Sold	HOWARD HORN
See the definition of "person" in paragraph (a) of Rule 144. Information is to be given not only as to the person for whose account the securities are to be sold but also as to all other persons included in that definition. In addition, information shall be given as to sales by all persons whose sales are required by paragraph (e) of Rule 144 to be aggregated with sales for the account of the person filing this notice.
Relationship to Issuer	Officer

144: Securities Information

Title of the Class of Securities To Be Sold	Name and Address of the Broker	Number of Shares or Other Units To Be Sold	Aggregate Market Value	Number of Shares or Other Units Outstanding	Approximate Date of Sale	Name the Securities Exchange
Common	Morgan Stanley Smith Barney LLC Executive Financial Services 1 New York Plaza 8th Floor New York NY 10004	4683	116606.70	96629788	05/01/2026	NASDAQ

Furnish the following information with respect to the acquisition of the securities to be sold and with respect to the payment of all or any part of the purchase price or other consideration therefor:

144: Securities To Be Sold

Title of the Class	Date you Acquired	Nature of Acquisition Transaction	Name of Person from Whom Acquired	Is this a Gift?	Date Donor Acquired	Amount of Securities Acquired	Date of Payment	Nature of Payment *
Common	10/09/2024	Restricted Stock	ISSUER			1743	10/09/2024	Not Applicable
Common	10/09/2025	Restricted Stock	ISSUER			1343	10/09/2025	Not Applicable
Common	03/01/2026	Restricted Stock	ISSUER			939	03/01/2026	Not Applicable
Common	03/01/2026	Performance Shares	ISSUER			658	03/01/2026	Not Applicable

* If the securities were purchased and full payment therefor was not made in cash at the time of purchase, explain in the table or in a note thereto the nature of the consideration given. If the consideration consisted of any note or other obligation, or if payment was made in installments describe the arrangement and state when the note or other obligation was discharged in full or the last installment paid.

Furnish the following information as to all securities of the issuer sold during the past 3 months by the person for whose account the securities are to be sold.

144: Securities Sold During The Past 3 Months

Name and Address of Seller	Title of Securities Sold	Date of Sale	Amount of Securities Sold	Gross Proceeds
HOWARD HORN 60 Leveroni Court Novato CA 94949	Common	04/01/2026	4683	98202.51
HOWARD HORN 60 Leveroni Court Novato CA 94949	Common	03/03/2026	1635	36624.00
HOWARD HORN 60 Leveroni Court Novato CA 94949	Common	03/02/2026	3119	70302.26
HOWARD HORN 60 Leveroni Court Novato CA 94949	Common	03/02/2026	5290	120616.98
HOWARD HORN 60 Leveroni Court Novato CA 94949	Common	02/02/2026	3061	72117.16

144: Remarks and Signature

Remarks
Date of Notice	05/01/2026
Date of Plan Adoption or Giving of Instruction, If Relying on Rule 10b5-1	09/02/2025
ATTENTION:
The person for whose account the securities to which this notice relates are to be sold hereby represents by signing this notice that he does not know any material adverse information in regard to the current and prospective operations of the Issuer of the securities to be sold which has not been publicly disclosed. If such person has adopted a written trading plan or given trading instructions to satisfy Rule 10b5-1 under the Exchange Act, by signing the form and indicating the date that the plan was adopted or the instruction given, that person makes such representation as of the plan adoption or instruction date.
Signature	/s/ Howard Horn
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)