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RA Capital boosts stake in Parabilis Medicines (PBLS) with stock buys

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(Very Positive)
Form Type
4

Rhea-AI Filing Summary

RA Capital-affiliated funds reported open-market purchases of 244,593 shares of Parabilis Medicines voting common stock from July 20–22, 2026, at weighted average prices around $27–30 per share. The shares are held indirectly by RA Capital Healthcare Fund LP, with the adviser and principals disclaiming beneficial ownership beyond their pecuniary interests.

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Insider RA CAPITAL MANAGEMENT, L.P., RA Capital Healthcare Fund LP, RA Capital Nexus Fund III, L.P., Kolchinsky Peter, Shah Rajeev M.
Role Director, 10% Owner | Director, 10% Owner | Director | Director, 10% Owner | Director, 10% Owner
Bought 244,593 shs ($6.92M)
Type Security Shares Price Value
Purchase Voting Common Stock F8, F2, F3 47,250 $29.77 $1.41M
Purchase Voting Common Stock F5, F2, F3 21,696 $27.96 $607K
Purchase Voting Common Stock F6, F2, F3 6,504 $29.17 $190K
Purchase Voting Common Stock F7, F2, F3 37,723 $30.00 $1.13M
Purchase Voting Common Stock F1, F2, F3 98,433 $27.13 $2.67M
Purchase Voting Common Stock F4, F2, F3 32,987 $27.72 $914K
holding Voting Common Stock F2, F9 -- -- --
Holdings After Transaction: Voting Common Stock — 29,177,964 shares (Indirect, See footnotes)
Footnotes (9)
  1. F1. The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $26.53 to $27.50 inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in this footnote.
  2. F2. RA Capital Management, L.P. (the "Adviser") is the investment manager for RA Capital Healthcare Fund, L.P. (the "Fund") and RA Capital Nexus Fund III, L.P. (the "Nexus Fund III"). The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. Each of the Adviser, the Adviser GP, the Fund, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaims beneficial ownership of any of the reported securities, except to the extent of its or his respective pecuniary interest therein.
  3. F3. Held directly by the Fund.
  4. F4. The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $27.55 to $27.87 inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in this footnote.
  5. F5. The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $27.46 to $28.34 inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in this footnote.
  6. F6. The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $28.83 to $29.79 inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in this footnote.
  7. F7. The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $29.97 to $30.00 inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in this footnote.
  8. F8. The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $29.35 to $30.00 inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in this footnote.
  9. F9. Held directly by Nexus Fund III.
Total shares purchased 244593 shares Aggregate indirect purchases of Voting Common Stock across six transactions
Purchase on 2026-07-20 at $27.1300 98433 shares Indirect open-market purchase; weighted average price $27.1300 per share with trades from $26.53 to $27.50
Purchase on 2026-07-20 at $27.7200 32987 shares Indirect open-market purchase; weighted average price $27.7200 per share with trades from $27.55 to $27.87
Purchase on 2026-07-21 at $27.9600 21696 shares Indirect open-market purchase; weighted average price $27.9600 per share with trades from $27.46 to $28.34
Purchase on 2026-07-21 at $29.1700 6504 shares Indirect open-market purchase; weighted average price $29.1700 per share with trades from $28.83 to $29.79
Purchase on 2026-07-21 at $30.0000 37723 shares Indirect open-market purchase; weighted average price $30.0000 per share with trades from $29.97 to $30.00
Purchase on 2026-07-22 at $29.7700 47250 shares Indirect open-market purchase; weighted average price $29.7700 per share with trades from $29.35 to $30.00
Number of reported purchase transactions 6 transactions All reported non-derivative entries coded as open-market or private purchases
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.
beneficial ownership financial
"each disclaims beneficial ownership of any of the reported securities"
Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.
pecuniary interest financial
"except to the extent of its or his respective pecuniary interest therein"
investment manager financial
"RA Capital Management, L.P. is the investment manager for RA Capital Healthcare Fund"

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FAQ

What insider buying in PBLS did RA Capital report in this Form 4?

RA Capital-managed entities reported indirect open-market purchases of 244,593 Parabilis Medicines (PBLS) voting common shares between July 20 and July 22, 2026, across six transactions, all coded as purchases of non-derivative voting common stock.

At what prices were PBLS shares purchased in RA Capital's Form 4?

The PBLS purchases occurred at weighted average prices from about $27.13 to $30.00 per share. Footnotes state each block comprised multiple trades within ranges between $26.53 and $30.00, with full trade-by-trade detail available on request to the issuer or SEC staff.

Who actually holds the PBLS shares reported in RA Capital's Form 4?

The purchased PBLS shares are held directly by RA Capital Healthcare Fund LP, with RA Capital Management, L.P. acting as investment manager. A separate reported indirect holding is held directly by RA Capital Nexus Fund III, L.P., as noted in the ownership footnotes.

How does RA Capital describe its beneficial ownership of PBLS in this filing?

RA Capital Management, its general partner, the RA Capital Healthcare Fund LP, RA Capital Nexus Fund III, L.P., and two managing members disclaim beneficial ownership of the reported PBLS securities except to the extent of each party’s respective pecuniary interest in those securities.

Were the PBLS trades in this Form 4 made under a Rule 10b5-1 plan?

The Rule 10b5-1 checkbox for this PBLS Form 4 is not marked as affirming a plan. The filing characterizes the transactions as open-market or private purchases, without identifying them as executed pursuant to a Rule 10b5-1 trading plan.
SEC Form 4
FORM 4UNITED 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*
RA CAPITAL MANAGEMENT, L.P.

(Last)(First)(Middle)
200 BERKELEY STREET, 18TH FLOOR

(Street)
BOSTON MASSACHUSETTS 02116

(City)(State)(Zip)

UNITED STATES

(Country)
2. Issuer Name and Ticker or Trading Symbol
Parabilis Medicines, Inc. [ PBLS ]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
XDirectorX10% Owner
Officer (give title below)Other (specify below)
2a. Foreign Trading Symbol
3. Date of Earliest Transaction (Month/Day/Year)
07/20/2026
6. Individual or Joint/Group Filing (Check Applicable Line)
Form filed by One Reporting Person
XForm 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)
CodeVAmount(A) or (D)Price
Voting Common Stock07/20/2026P98,433A$27.13(1)26,383,526ISee footnotes(2)(3)
Voting Common Stock07/20/2026P32,987A$27.72(4)26,416,513ISee footnotes(2)(3)
Voting Common Stock07/21/2026P21,696A$27.96(5)26,438,209ISee footnotes(2)(3)
Voting Common Stock07/21/2026P6,504A$29.17(6)26,444,713ISee footnotes(2)(3)
Voting Common Stock07/21/2026P37,723A$30(7)26,482,436ISee footnotes(2)(3)
Voting Common Stock07/22/2026P47,250A$29.77(8)26,529,686ISee footnotes(2)(3)
Voting Common Stock2,648,278ISee footnotes(2)(9)
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)
CodeV(A)(D)Date ExercisableExpiration DateTitleAmount or Number of Shares
1. Name and Address of Reporting Person*
RA CAPITAL MANAGEMENT, L.P.

(Last)(First)(Middle)
200 BERKELEY STREET, 18TH FLOOR

(Street)
BOSTON MASSACHUSETTS 02116

(City)(State)(Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer
XDirectorX10% Owner
Officer (give title below)Other (specify below)
1. Name and Address of Reporting Person*
RA Capital Healthcare Fund LP

(Last)(First)(Middle)
C/O RA CAPITAL MANAGEMENT, L.P.
200 BERKELEY STREET, 18TH FLOOR

(Street)
BOSTON MASSACHUSETTS 02116

(City)(State)(Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer
XDirectorX10% Owner
Officer (give title below)Other (specify below)
1. Name and Address of Reporting Person*
RA Capital Nexus Fund III, L.P.

(Last)(First)(Middle)
C/O RA CAPITAL MANAGEMENT, L.P.
200 BERKELEY STREET, 18TH FLOOR

(Street)
BOSTON MASSACHUSETTS 02116

(City)(State)(Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer
XDirector10% Owner
Officer (give title below)Other (specify below)
1. Name and Address of Reporting Person*
Kolchinsky Peter

(Last)(First)(Middle)
C/O RA CAPITAL MANAGEMENT, L.P.
200 BERKELEY STREET, 18TH FLOOR

(Street)
BOSTON MASSACHUSETTS 02116

(City)(State)(Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer
XDirectorX10% Owner
Officer (give title below)Other (specify below)
1. Name and Address of Reporting Person*
Shah Rajeev M.

(Last)(First)(Middle)
C/O RA CAPITAL MANAGEMENT, L.P.
200 BERKELEY STREET, 18TH FLOOR

(Street)
BOSTON MASSACHUSETTS 02116

(City)(State)(Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer
XDirectorX10% 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 purchased in multiple transactions at prices ranging from $26.53 to $27.50 inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in this footnote.
2. RA Capital Management, L.P. (the "Adviser") is the investment manager for RA Capital Healthcare Fund, L.P. (the "Fund") and RA Capital Nexus Fund III, L.P. (the "Nexus Fund III"). The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. Each of the Adviser, the Adviser GP, the Fund, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaims beneficial ownership of any of the reported securities, except to the extent of its or his respective pecuniary interest therein.
3. Held directly by the Fund.
4. The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $27.55 to $27.87 inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in this footnote.
5. The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $27.46 to $28.34 inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in this footnote.
6. The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $28.83 to $29.79 inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in this footnote.
7. The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $29.97 to $30.00 inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in this footnote.
8. The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $29.35 to $30.00 inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in this footnote.
9. Held directly by Nexus Fund III.
Remarks:
Dr. Jake Simson, a Partner of the Adviser, serves on the Issuer's board of directors.
/s/ Peter Kolchinsky, Manager of RA Capital Management, L.P.07/22/2026
/s/ Peter Kolchinsky, Manager of RA Capital Healthcare Fund GP, LLC the General Partner of RA Capital Healthcare Fund, L.P.07/22/2026
/s/ Peter Kolchinsky, Manager of RA Capital Nexus Fund III GP, LLC the General Partner of RA Capital Nexus Fund III, L.P.07/22/2026
/s/ Peter Kolchinsky, individually07/22/2026
/s/ Rajeev Shah, individually07/22/2026
** Signature of Reporting PersonDate
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)