$DYN

$16.94 +$1.22 (7.76%) Close

$DYN Overview Financial Statements SEC Filings Executives News Red Flags Capital Raising Ownership Insider Transactions Congressional Trades

Ownership

13F as of Q2 2026 · 186.7M shares outstanding

Who owns DYN?

By type of holder

Institutions 100.0% Insiders 0.0% Everyone else 0.0%

Concentration Top 10 holders own 53.9%

T. Rowe Price Investment Management, Inc. 16.6% · BlackRock, Inc. 6.6%

Institutional ownership

100.0%

0 pts vs last qtr

Institutional holders

244

+16 vs last qtr

Net shares bought

+2.7M

by institutions in Q2 2026

New / sold out

48 / 32

positions opened vs closed

How is ownership changing?

Institutions, last 8 quarters

Biggest buyers in Q2 2026

Jupiter Topco LLC NEW +12.0M
FMR LLC +2.3M

Biggest sellers in Q2 2026

Janus Henderson Group PLC SOLD OUT −13.6M
Atlas Venture Life Science Advisors, LLC −2.3M

Who is planning to sell?

Notices of proposed sale, last 12 months

$175M

86 notices from 9 people

Shares covered

8.0M

4.26% of the company

Arranged in advance

99%

of the value is under a 10b5-1 plan

Under a 10b5-1 plan No plan

Largest proposed sellers

Atlas Venture Fund XI, LP Shareholder 10b5-1 $75.7M
ForDyne B.V. Affiliate 10b5-1 $43.3M

Every notice on Red Flags →

A Form 144 is notice of a planned sale, not the sale itself. What insiders actually sold is on Insider Transactions.

Is your stake being diluted?

There are not yet two fiscal years of reported share counts for Dyne Therapeutics, Inc..

How patient are the owners?

Institutional shares by how long they've been held

5+ years30% 3–5 years19% 1–3 years34% Under 1 year18%

Quarterly turnover

15.0%

of institutional shares changed hands

Top 10 managers, median time held

4.5 years

Super Investors

Investment managers reporting DYN on Form 13F

Holder	Shares	% of company	Change vs last qtr	Held since	% of their book
TR T. Rowe Price Investment Management, Inc.	30.9M	16.55%	+126.5K (+0.4%)	2025	0.5%
Shares held by quarter Peak holding30.9M (Q2'26) Change over 8 quarters+30.9M Share of the company16.550% T. Rowe Price Investment Management, Inc.'s full portfolio →
JH Janus Henderson Group PLC	—	—	SOLD OUT	—	0.0%
Shares held by quarter Peak holding14.7M (Q3'25) Change over 8 quarters−6.8M Janus Henderson Group PLC's full portfolio →

T. Rowe Price Investment Management, Inc.

30.9M

% of company

16.55%

Change vs last qtr

+126.5K (+0.4%)

Held since

2025

Janus Henderson Group PLC

—

% of company

—

Change vs last qtr

SOLD OUT

Held since

—

28 more super investors behind a free account

See every manager holding Dyne Therapeutics, Inc., how their position has changed, and how long they've held it.

Institutional Funds

Mutual funds and ETFs reporting DYN on Form N-PORT; together they hold 39.2% of the company

Fund	Position value	Shares	% of company	% of the fund	As of
TR T. Rowe Price Small-Cap Stock Fund, Inc. T. Rowe Price Small-Cap Stock Fund, Inc.	$156M	7.0M	3.75%	1.67%	June 30, 2026
TR T. Rowe Price Small-Cap Value Fund, Inc. T. Rowe Price Small-Cap Value Fund, Inc.	$102M	4.6M	2.46%	0.97%	June 30, 2026

T. Rowe Price Small-Cap Stock Fund, Inc.

Position value

$156M

% of company

3.75%

% of the fund

1.67%

As of

June 30, 2026

T. Rowe Price Small-Cap Value Fund, Inc.

Position value

$102M

% of company

2.46%

% of the fund

0.97%

As of

June 30, 2026

23 more funds behind a free account

See every fund holding Dyne Therapeutics, Inc. and how much of the fund the position is.

Insiders and 5%+ holders

From Forms 3/4/5 and Schedules 13D/G

Holder	Shares	% of company	Change vs last qtr	8 quarters	Held since	% of their book
KD Kersten Dirk Insider	3.6M	1.92%	—	—	—	—
Insider holdings come from Form 3/4/5 filings, which are not quarterly. Share of the company1.920% Kersten Dirk's insider activity →
CJ Cox John Insider	429.5K	0.23%	—	—	—	—
Insider holdings come from Form 3/4/5 filings, which are not quarterly. Share of the company0.230% Cox John's insider activity →

Kersten Dirk

Insider

3.6M

% of company

1.92%

Change vs last qtr

—

Held since

—

Cox John

Insider

429.5K

% of company

0.23%

Change vs last qtr

—

Held since

—

7 more holders behind a free account

See every insider and 5%+ holder of Dyne Therapeutics, Inc..

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