RA Capital funds lift Parabilis Medicines (PBLS) common equity exposure

Rhea-AI Filing Summary

Parabilis Medicines, Inc. disclosed that investment vehicles managed by RA Capital made substantial purchases and conversions into its Voting Common Stock. On June 11, 2026, RA Capital–related funds completed open‑market purchases totaling 21,188,750 shares of Voting Common Stock at $20.00 per share, held indirectly through the funds. On the same date, Series E and Series F Preferred Stock automatically converted into additional Voting Common Stock immediately prior to the closing of the IPO, with Series E converting at a 1 to 0.6524 ratio and Series F at a 1 to 0.6498 ratio, without payment of consideration. The RA Capital adviser and related entities disclaim beneficial ownership of the reported securities except to the extent of their pecuniary interest.

Insights

Biotech equity analyst

RA Capital–advised funds made large open‑market purchases and converted preferred stock into Parabilis common around the IPO.

Investment vehicles managed by RA Capital Management reported open‑market purchases of 21,188,750 shares of Parabilis Medicines Voting Common Stock at $20.00 per share. These positions are held indirectly through RA Capital Healthcare Fund LP and RA Capital Nexus Fund III, L.P., with the adviser and principals disclaiming beneficial ownership beyond their pecuniary interest.

In addition, Series E and Series F Preferred Stock automatically converted into Voting Common Stock immediately prior to the IPO closing, at ratios of 0.6524% and 0.6498% common shares per preferred share, respectively, without additional consideration. These conversions eliminate those preferred positions in favor of common equity exposure.

The combination of sizeable open‑market buying and full preferred conversion into common suggests RA Capital–associated funds increased their direct participation in Parabilis’s common equity structure around the IPO. Subsequent company filings may provide more detail on total ownership percentages and any future trading activity.

Insider Trade Summary

Net Buyer: 21,188,750 shares ($423,775,000)

Net Buy 8 txns

Insider RA CAPITAL MANAGEMENT, L.P., RA Capital Healthcare Fund LP, RA Capital Nexus Fund III, L.P., Kolchinsky Peter, Shah Rajeev M.

Role null | null | null | null | null

Bought 21,188,750 shs ($423.77M)

Type	Security	Shares	Price	Value
Conversion	Series E Preferred Stock	642,250	$0.00	--
Conversion	Series E Preferred Stock	160,562	$0.00	--
Conversion	Series F Preferred Stock	9,445,363	$0.00	--
Conversion	Series F Preferred Stock	1,666,829	$0.00	--
Conversion	Voting Common Stock	6,556,740	$0.00	--
Conversion	Voting Common Stock	1,187,881	$0.00	--
Purchase	Voting Common Stock	19,728,353	$20.00	$394.57M
Purchase	Voting Common Stock	1,460,397	$20.00	$29.21M

Holdings After Transaction: Series E Preferred Stock — 0 shares (Indirect, See footnotes); Series F Preferred Stock — 0 shares (Indirect, See footnotes); Voting Common Stock — 6,556,740 shares (Indirect, See footnotes)

Footnotes (1)

1. Each share of Series E Preferred Stock automatically converted into Voting Common Stock on a 1 to 0.6524 basis immediately prior to the closing of the IPO and without payment of consideration. The Series E Preferred Stock has no expiration date. Each share of Series F Preferred Stock automatically converted into shares of Voting Common Stock on a 1 to 0.6498 basis immediately prior to the closing of the IPO and without payment of consideration. The Series F Preferred Stock has no expiration date. 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. Held directly by the Fund. Held directly by Nexus Fund III.

Key Figures

Open-market purchases: 21,188,750 shares Purchase price: $20.00 per share Single purchase block: 1,460,397 shares +5 more

8 metrics

Open-market purchases 21,188,750 shares Voting Common Stock bought on June 11, 2026

Purchase price $20.00 per share Voting Common Stock open-market transactions

Single purchase block 1,460,397 shares Voting Common Stock open-market buy, indirect ownership

Second purchase block 19,728,353 shares Voting Common Stock open-market buy, indirect ownership

Series F conversion ratio 1 to 0.6498 Series F Preferred to Voting Common Stock

Series E conversion ratio 1 to 0.6524 Series E Preferred to Voting Common Stock

Series F underlying common 6,137,734 shares Voting Common Stock from Series F conversion

Series E underlying common 523,757 shares Voting Common Stock from Series E conversion

Key Terms

open-market purchase, derivative conversion, Series F Preferred Stock, Series E Preferred Stock, +2 more

6 terms

open-market purchase financial

"transaction_action": "open-market purchase""

An open-market purchase is when an investor or a company buys shares on a public stock exchange at the going market price, rather than through a private deal. It matters to investors because these purchases change how many shares are available, can push the stock price up or signal confidence from large buyers, and often affect per-share metrics like earnings—think of it like someone buying lots of apples off a grocery shelf, reducing supply and potentially raising the price.

derivative conversion financial

"transaction_action": "derivative conversion""

Series F Preferred Stock financial

"security_title": "Series F Preferred Stock""

Series F preferred stock is a class of company shares that gives holders priority over common shareholders for dividend payments and for getting money back if the company is sold or liquidated, much like a ticket that moves you to the front of the line. These shares often carry a fixed dividend and special rights—sometimes including conversion into common stock—so investors consider them when weighing income, downside protection and potential ownership dilution.

Series E Preferred Stock financial

"security_title": "Series E Preferred Stock""

Series E preferred stock is a specific class of company shares created in a later funding round that gives holders priority over common shareholders for payments and assets, often including a fixed dividend and special conversion or voting rights. Think of it as a VIP ticket that gets paid first and may convert into regular shares later; investors watch these terms because they affect potential returns, risk in a sale or bankruptcy, and control of the company.

IPO financial

"immediately prior to the closing of the IPO"

An initial public offering (IPO) is the process by which a private company sells its shares to the public for the first time, making its ownership available on the stock market. This allows the company to raise money from a wide range of investors to fund growth or other goals. For investors, an IPO offers a chance to buy into a company early in its public journey, potentially benefiting if the company grows in value.

pecuniary interest financial

"except to the extent of its or his respective pecuniary interest therein"

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Form 4 Insider Transactions: What Each Field Means →

SEC Form 4

FORM 4

UNITED 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)

X	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
06/11/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

	Form filed by One Reporting Person
X	Form 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)
			Code	V	Amount	(A) or (D)	Price
Voting Common Stock	06/11/2026		C		6,556,740	A	(1)(2)	6,556,740	I	See footnotes(3)(4)
Voting Common Stock	06/11/2026		C		1,187,881	A	(1)(2)	1,187,881	I	See footnotes(3)(5)
Voting Common Stock	06/11/2026		P		19,728,353	A	$20	26,285,093	I	See footnotes(3)(4)
Voting Common Stock	06/11/2026		P		1,460,397	A	$20	2,648,278	I	See footnotes(3)(5)

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)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Series E Preferred Stock	(1)	06/11/2026		C			642,250	(1)	(1)	Voting Common Stock	419,006	(1)	0	I	See footnotes(3)(4)
Series E Preferred Stock	(1)	06/11/2026		C			160,562	(1)	(1)	Voting Common Stock	104,751	(1)	0	I	See footnotes(3)(5)
Series F Preferred Stock	(2)	06/11/2026		C			9,445,363	(2)	(2)	Voting Common Stock	6,137,734	(2)	0	I	See footnotes(3)(4)
Series F Preferred Stock	(2)	06/11/2026		C			1,666,829	(2)	(2)	Voting Common Stock	1,083,130	(2)	0	I	See footnotes(3)(5)

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

X	Director	X	10% 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

X	Director	X	10% 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

X	Director		10% 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

X	Director	X	10% 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

X	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

Explanation of Responses:

1. Each share of Series E Preferred Stock automatically converted into Voting Common Stock on a 1 to 0.6524 basis immediately prior to the closing of the IPO and without payment of consideration. The Series E Preferred Stock has no expiration date.

2. Each share of Series F Preferred Stock automatically converted into shares of Voting Common Stock on a 1 to 0.6498 basis immediately prior to the closing of the IPO and without payment of consideration. The Series F Preferred Stock has no expiration date.

3. 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.

4. Held directly by the Fund.

5. 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.	06/15/2026
	/s/ Peter Kolchinsky, Manager of RA Capital Healthcare Fund GP, LLC the General Partner of RA Capital Healthcare Fund, L.P.	06/15/2026
	/s/ Peter Kolchinsky, Manager of RA Capital Nexus Fund III GP, LLC the General Partner of RA Capital Nexus Fund III, L.P.	06/15/2026
	/s/ Peter Kolchinsky, individually	06/15/2026
	/s/ Rajeev Shah, individually	06/15/2026
	** Signature of Reporting Person	Date
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)

FAQ

What did RA Capital–managed funds do in Parabilis Medicines (PBLS) on June 11, 2026?

RA Capital–managed funds reported large open‑market purchases of Parabilis Voting Common Stock and conversions of Series E and F Preferred Stock into common, increasing their indirect common equity exposure around the company’s IPO.

How many Parabilis Medicines (PBLS) shares did RA Capital–managed funds buy?

They reported open‑market purchases totaling 21,188,750 shares of Parabilis Voting Common Stock at $20.00 per share, held indirectly through RA Capital Healthcare Fund LP and RA Capital Nexus Fund III, L.P.

At what price were Parabilis Medicines (PBLS) shares purchased by RA Capital–managed funds?

The reported open‑market purchases of Parabilis Voting Common Stock were executed at $20.00 per share. These transactions occurred on June 11, 2026, and are held indirectly through RA Capital–advised investment funds.

What happened to Parabilis Medicines (PBLS) Series E Preferred Stock in this Form 4?

Each share of Series E Preferred Stock automatically converted into Voting Common Stock on a 1 to 0.6524 basis immediately before the IPO closing, with no additional consideration paid and no stated expiration date for the preferred shares.

How was Parabilis Medicines (PBLS) Series F Preferred Stock treated in the reported transactions?

Each share of Series F Preferred Stock automatically converted into Voting Common Stock on a 1 to 0.6498 basis immediately prior to the IPO closing, without payment of additional consideration and with no expiration date for the preferred shares before conversion.

Do RA Capital and its principals claim full beneficial ownership of the Parabilis (PBLS) securities?

No. RA Capital Management, its general partner, the related funds, and principals Peter Kolchinsky and Rajeev Shah each disclaim beneficial ownership of the reported securities, except to the extent of each party’s respective pecuniary interest in those holdings.