Alex Keun Mo Yang - 29 Jan 2026 Form 3 Insider Report for Polaryx Therapeutics, Inc. (PLYX)

Role
Chief Executive Officer, Director, 10%+ Owner
Signature
/s/ Alex Keun Mo Yang
Issuer symbol
PLYX
Transactions as of
29 Jan 2026
Net transactions value
$0
Form type
3
Filing time
29 Jan 2026, 18:07:38 UTC
SEC
View on sec.gov

Reporting Owners (2)

Name Relationship Address Signature Signature date CIK
Yang Alex Keun Mo Chief Executive Officer, Director, 10%+ Owner SOUTH TOWER, 140 E RIDGEWOOD AVENUE,, SUITE 415, PARAMUS /s/ Alex Keun Mo Yang 29 Jan 2026 0002103399
Mstone Partners Healthcare Ltd Director, 10%+ Owner 7/F, 80 GLOUCESTER ROAD, WANCHAI, HONG KONG /s/ Alex Keun Mo Yang, Chief Executive Officer of Mstone Partners Healthcare Limited 29 Jan 2026 0002104809

Transactions Table

Type Sym Class Transaction Value $ Shares Change % * Price $ Shares After Date Ownership Footnotes
holding PLYX Common Stock 1,400,000 29 Jan 2026 Direct F1
holding PLYX Common Stock 22,452,954 29 Jan 2026 By Mstone Partners Healthcare Limited F2
holding PLYX Common Stock 183,560 29 Jan 2026 By MBstone Biotech Flagship Limited F3
holding PLYX Common Stock 108,282 29 Jan 2026 By Mstone Pediaorphan Singapore I Pte. Limited F4
* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id Content
F1 Includes (i) 148,500 restricted stock units ("RSUs"), which will vest on March 1, 2026, (ii) 330,000 RSUs, which will vest in two equal installments on November 1, 2026 and November 1, 2027 and (iii) 450,000 RSUs, which will vest in four equal installments on September 1, 2026, September 1, 2027, September 1, 2028 and September 1, 2029, in each case subject to the Reporting Person's continued service to the Issuer or its subsidiaries, Mstone Partners Healthcare Limited ("Mstone") or its affiliates, or Curestone Partners Platform Limited or its affiliates. The RSUs are not deliverable unless and until the Issuer consummates a change in control within seven years of the grant date of such RSUs.
F2 Alex Keun Mo Yang is the founder and Chief Executive Officer of Mstone. Mr. Yang disclaims beneficial ownership over any of the reported securities, except to the extent of his pecuniary interest therein.
F3 Mr. Yang is the Chief Executive Officer of MBstone Biotech Flagship Limited. Mr. Yang disclaims beneficial ownership over any of the reported securities, except to the extent of his pecuniary interest therein.
F4 Mr. Yang is the Chief Executive Officer of Mstone Pediaorphan Singapore I Pte. Limited. Mr. Yang disclaims beneficial ownership over any of the reported securities owned, except to the extent of his pecuniary interest therein.

Remarks:

Exhibit 24 - Power of Attorney Mstone, MBstone Biotech Flagship Limited and Mstone Pediaorphan Singapore I Pte. Limited may each be deemed a director by deputization of the Issuer by virtue of the fact that Mr. Yang serves on the board of directors of the Issuer and is the Chief Executive Officer of each of the entities.