WESTFIELD CAPITAL MANAGEMENT CO LP

Position in ALNY — Alnylam Pharmaceuticals, Inc.

CIK 1177719 BOSTON, MA

Position in ALNY

as of Jun 30, 2026 · filed Aug 12, 2026 Compact

Position Value

$75,974,854

-$5,266,634 QoQ

Shares Held

252,383

+2.8% QoQ

Ownership

0.189%

of shares outstanding

% of Portfolio

0.25%

of 13F equity value

Holder Rank

#65

of 784 holders

Holding Since

Mar 2020

8 quarters on record

Voting authority Sole 80% Shared 0% None 20%

Healthcare · as of Jun 30, 2026

WESTFIELD CAPITAL MANAGEMENT CO LP holds $3,083,455,798 across 23 Biotechnology names. ALNY ranks #10 (2.5% of the industry book) .

#	Ticker	Company	Shares	Value (USD)
1	ASND	Ascendis Pharma A/S	4,798,267	$1,279,793,774
2	RYTM	Rhythm Pharmaceuticals, Inc.	2,208,595	$245,220,302
3	ABVX	Abivax S.A.	1,309,825	$174,547,279
4	INSM	INSMED Inc	1,629,561	$173,743,793
5	PTCT	Ptc Therapeutics, Inc.	1,956,156	$159,563,644
6	PCVX	Vaxcyte, Inc.	2,472,428	$143,722,239
7	LEGN	Legend Biotech Corp	4,430,063	$127,940,219
8	RVMD	Revolution Medicines, Inc.	600,821	$112,521,756

8 filing rows on record

Report Date	Value (USD)	Shares	Change	Type	Discretion	Filed
2026-06-30	$75,974,854	252,383	+2.8%	Shares	Sole	2026-08-12
2026-03-31	$81,241,488	245,539	+162.8%	Shares	Sole	2026-05-11
2025-12-31	$37,158,006	93,444	+6.3%	Shares	Sole	2026-02-11
2025-09-30	$40,086,048	87,908	-53.0%	Shares	Sole	2025-11-12
2025-06-30	$60,947,851	186,905	-2.7%	Shares	Sole	2025-08-12
2025-03-31	$51,890,283	192,172	-11.1%	Shares	Sole	2025-05-09
2024-12-31	$50,856,609	216,126	+55.9%	Shares	Sole	2025-02-11
2020-03-31	$15,093,576	138,664	—	Shares	Sole	2020-05-14
No filing history on record for this holder in this stock.