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Catalys Pacific, LLC — 13F Holdings & Portfolio

CIK 2011385 · latest 13F-HR filed 2026-08-05

Backtest portfolio

Catalys Pacific, LLC manages $229.5M in 13F-reported U.S. long-equity assets across 2 reported positions as of its 2026-06-30 13F-HR filing. Its largest disclosed positions are MLYS (92.94%), PHAT (7.06%).

AUM is the long-equity portion reported on Form 13F-HR. Excludes short positions, cash, foreign holdings, and non-13F assets. For informational purposes only — not investment advice.

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AUM
$229.5M

Long-equity book

Holdings
2

Distinct positions

Period
2026-06-30

Filed 2026-08-05

Q/Q Activity
+0 / −0 / ↑0 / ↓0

vs 2026-03-31

Portfolio charts

Latest quarter's book, what changed, and how the portfolio has evolved across filings.

Portfolio map

Q2 26
MLYS92.9% · 0%PHAT7.1% · 0%

Box size = position value; colour = change in share count vs the prior quarter (green added, red trimmed, blue new). Rows split across managers or share classes are combined. Click a box for the stock.

Sector mix

% of 13F value

Sectors from each company's SIC code; funds and ETFs grouped separately.

Biggest buys and sells

Q1 26 → Q2 26

Estimated from the change in shares held × the quarter-end price, so price moves alone don't count as buying. New and exited positions are included.

13F assets and positions

4 quarters

Total reported 13F value (bars) and number of positions (line) each quarter. Value changes include market moves.

Top positions over time

reported value

The eight largest current positions, valued at each quarter end.

Concentration

top 10 = 100%

Cumulative share of the portfolio held in the largest N positions.

Firm Profile & Key People

As of the firm’s regulatory filing dated Mar 24, 2026.

Address
8-14
MINAMI-AOYAMA 3-CHOME MINATO-KU
TOKYO 107-0062
Japan
Phone
81-50-1744-2996
Website
Name Title / Status Ownership Type
Slingsby, Brian, Taylor ControlMANAGING DIRECTOR
since Apr 2018
75% or moreIndividual
Ownership & leadership changes · 2 filings with changes since May 6, 2019

From the firm’s regulatory filings, newest first. Dates are filing dates: a filing that no longer lists someone does not say when they left.

Mar 27, 2024 filing
  • ChangedSlingsby, Brian, Taylor · title MANAGING PARTNER → MANAGING DIRECTOR
Mar 23, 2022 filing
  • ChangedSlingsby, Brian, Taylor · title MANAGING MEMBER → MANAGING PARTNER
May 6, 2019 filing (earliest on record)
  • ListedSlingsby, Brian, Taylor · MANAGING MEMBER · 75% or more · control person

Quarter-over-quarter changes

Changes in reported position value vs the prior 13F, so price moves count too, not just shares bought or sold.

Top Adds (vs prior quarter)

  • No increased positions.
Show all 0 →

Top Trims

  • No decreased positions.
Show all 0 →

New Positions

  • No new positions this quarter.
Show all 0 →

Exited Positions

  • No exits this quarter.
Show all 0 →

Catalys Pacific, LLC Holdings (2026-06-30)

Rows tagged Call or Put are options positions, not stock. Per SEC Form 13F-HR, Value shows the notional value of the underlying (shares covered × underlying price), not the option premium. Shares is the number of underlying shares covered (divide by 100 for contract count).

# Issuer Symbol CUSIP Value Weight Shares Type
1 Mineralys Therapeutics, Inc. MLYS 603170101 $213.2M 92.94% 7,903,838 SH
2 Phathom Pharmaceuticals, Inc. PHAT 71722W107 $16.2M 7.06% 1,493,854 SH
Filing History
Period Filed AUM Holdings Accession
2026-06-30 2026-08-05 $229.5M 2 0001104659-26-090867
2026-03-31 2026-05-14 $230.7M 2 0001104659-26-060911
2025-12-31 2026-02-10 $310.5M 2 0001104659-26-012485
2025-09-30 2025-11-14 $351.4M 2 0001104659-25-112029
Filer Information
Address
VORT MINAMIAOYAMA III 4F
8-14, MINAMI-AOYAMA 3-CHOME, MINATO-KU
TOKYO 107-0062
Phone
81-50-1744-2996
Filing Manager
Catalys Pacific, LLC
TOKYO, M0
Signatory
Brian Taylor Slingsby
Managing Director