Issuer Free Writing Prospectus

Filed Pursuant to Rule 433

Registration Statement No. 333-297820

Relating to the

Preliminary Prospectus Supplements

Dated September 23, 2026

(To Prospectus Dated July 29, 2026)

PRICING TERM SHEET

September 23, 2026

Viking Therapeutics, Inc.

Offerings of

7,857,143 Shares of Common Stock

and

$225,000,000 Aggregate Principal Amount of

2.00% Convertible Senior Notes due 2032

The information in this pricing term sheet supplements Viking Therapeutics, Inc.’s preliminary prospectus supplement, dated September 23, 2026 (the “Common Stock Preliminary Prospectus Supplement”), relating to an offering of common stock (the “Common Stock Offering”), and Viking Therapeutics, Inc.’s preliminary prospectus supplement, dated September 23, 2026 (the “Convertible Note Preliminary Prospectus Supplement,” and, together with the Common Stock Preliminary Prospectus Supplement, the “Preliminary Prospectus Supplements”), relating to an offering of convertible senior notes due 2032 (the “Convertible Note Offering”), and supersedes the information in the applicable Preliminary Prospectus Supplement to the extent inconsistent with the information in that Preliminary Prospectus Supplement. Terms used, but not defined, in this pricing term sheet have the respective meanings set forth in the applicable Preliminary Prospectus Supplement. As used in this pricing term sheet, “we,” “our” and “us” refer to Viking Therapeutics, Inc. and not to its subsidiaries. Viking Therapeutics, Inc. has increased the size of the Common Stock Offering from $200,000,000 to $275,000,005 (or $316,249,990 if the underwriters of the Common Stock Offering fully exercise their option to purchase additional Common Stock). In addition, Viking Therapeutics, Inc. has increased the size of the Convertible Note Offering from $200,000,000 to $225,000,000 (or $258,750,000 if the underwriters of the Convertible Note Offering fully exercise their over-allotment option to purchase additional Notes). The final prospectus supplements relating to the Common Stock Offering and the Convertible Note Offering will reflect conforming changes relating to such increase in the size of the Common Stock Offering and the Convertible Note Offering, respectively.

Common Stock Offering

Convertible Note Offering  

If such make-whole fundamental change effective date or stock price is not set forth in the table above, then:

Notwithstanding anything to the contrary, in no event will the conversion rate be increased to an amount that exceeds 28.5714 shares of our Common Stock per $1,000 principal amount of Notes, which amount is subject to adjustment in the same manner as, and at the same time and for the same events for which, the conversion rate is required to be adjusted pursuant to the provisions described in the Convertible Note Preliminary Prospectus Supplement under the caption “Description of Notes—Conversion Rights—Conversion Rate Adjustments—Generally.”

* * *

We have filed a registration statement (including a prospectus) and the Preliminary Prospectus Supplements with the SEC for the offerings to which this communication relates. Before you invest, you should read the applicable Preliminary Prospectus Supplement and the prospectus in that registration statement and other documents we have filed with the SEC for more complete information about us and these offerings. You may get these documents free by visiting EDGAR on the SEC website at www.sec.gov. Alternatively, we, any underwriter or any dealer participating in the applicable offering will arrange to send you the applicable Preliminary Prospectus Supplement (or, when available, the applicable final prospectus supplement) and the accompanying prospectus upon request to: Morgan Stanley & Co. LLC at 180 Varick Street, 2nd Floor, New York, New York 10014, Attention: Prospectus Department; or J.P. Morgan Securities LLC, c/o Broadridge Financial Solutions, 1155 Long Island Avenue, Edgewood, New York 11717 or by email at prospectus-eq_fi@jpmchase.com and postsalemanualrequests@broadridge.com.

The information in this pricing term sheet is not a complete description of the Common Stock, the Common Stock Offering, the Notes or the Convertible Note Offering. You should rely only on the information contained or incorporated by reference in the applicable Preliminary Prospectus Supplement and the accompanying prospectus, as supplemented by this pricing term sheet, in making an investment decision with respect to the Common Stock or the Notes.

ANY DISCLAIMERS OR OTHER NOTICES THAT MAY APPEAR BELOW ARE NOT APPLICABLE TO THIS COMMUNICATION AND SHOULD BE DISREGARDED. SUCH DISCLAIMERS OR OTHER NOTICES WERE AUTOMATICALLY GENERATED AS A RESULT OF THIS COMMUNICATION BEING SENT VIA BLOOMBERG OR ANOTHER EMAIL SYSTEM.