PRIMECAP Management Co/CA/ filed Amendment No. 18 to its Schedule 13G with the SEC on November 4, 2026, disclosing beneficial ownership of 9,879,855 shares of Xencor Inc common stock as of September 30, 2026.

Key Highlights

  • Aggregate beneficial ownership: PRIMECAP Management Co/CA/ reported 9,879,855 shares of Xencor Inc common stock beneficially owned.
  • Percent of class: The reported holdings represent 13.29% of Xencor Inc's outstanding common stock.
  • Sole voting and dispositive power: PRIMECAP holds sole voting power and sole dispositive power over all 9,879,855 shares, with zero shared voting or dispositive power reported.
  • Triggering event date: The date of event requiring this filing was September 30, 2026.
  • Notable sub-holder: According to the filing, PRIMECAP Odyssey Aggressive Growth Fund holds an interest of more than five percent of the total outstanding common stock of Xencor, Inc.
  • Filer classification: PRIMECAP is identified as an investment adviser (type "IA") organized in the United States.

PRIMECAP Management Discloses Amended Stake in Xencor Inc

According to the Schedule 13G filing, PRIMECAP Management Co/CA/, headquartered at 177 East Colorado Blvd., 11th Floor, Pasadena, California 91105, submitted Amendment No. 18 to its previously filed Schedule 13G covering shares of Xencor Inc (NASDAQ:XNCR), whose principal executive offices are located at 465 N. Halstead St., Suite 200, Pasadena, California 91107. The filing covers shares with CUSIP number 98401F105 and was signed by Jennifer A. Ottosen, Chief Compliance Officer, on November 4, 2026.

The filing reports that PRIMECAP beneficially owns 9,879,855 shares of Xencor Inc common stock, representing 13.29% of the class. All 9,879,855 shares are held with sole voting power and sole dispositive power; no shares are subject to shared voting or shared dispositive arrangements, according to the filing. The document notes that various persons have the right to receive, or the power to direct the receipt of, dividends from, or proceeds from the sale of, the reported securities, but that no single such person holds an interest exceeding five percent of the class, with one stated exception: PRIMECAP Odyssey Aggressive Growth Fund, which the filing identifies as holding an interest of more than five percent of the total outstanding common stock of Xencor, Inc.

PRIMECAP certified in the filing that the reported securities "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," as stated in the Item 10 certification.

What Was Disclosed

PRIMECAP Management Co/CA/ disclosed, via Amendment No. 18 to Schedule 13G, beneficial ownership of 9,879,855 Xencor Inc common shares, equal to 13.29% of the class, as of September 30, 2026, with PRIMECAP Odyssey Aggressive Growth Fund identified as holding more than five percent independently.