DYN SEC Filing News — Dyne Therapeutics, Inc.

Latest SEC filings for Dyne Therapeutics, Inc. (DYN) explained in plain English. Covers insider buying and selling (Form 4), proposed insider sales (Form 144), material company events (8-K), and quarterly & annual reports (10-Q / 10-K). StrongBuyAnalytics provides navigation and brief excerpts or summaries; original filings remain at the SEC/source links and were authored by their filers, not StrongBuyAnalytics. Filing dates shown are source dates. Coverage and detection can be delayed or incomplete because of SEC availability, amendments, parsing, caching, or outages. Latest source filing date shown: 2026-10-06.

Dyne Therapeutics, Inc., a clinical-stage neuromuscular disease company, focuses on discovering and developing therapeutics for neuromuscular diseases in the United States. The company is developing a portfolio of muscle disease therapeutics, including programs in myotonic dystrophy type 1; duchenne muscular dystrophy; facioscapulohumeral dystrophy; and Pompe disease, as well as rare skeletal muscle, and cardiac and metabolic muscle diseases using its FORCE platform that delivers disease-modifyi…
Sector: Healthcare Industry: Biotechnology Market Cap: $2.8B CIK: 1818794
20
Total Filings
1
Bullish Classifications
12
Bearish Classifications
9
Insider Transactions
1
Material Events (8-K)
0
Periodic Reports
Rule-based classifications for DYN currently lean bearish. Of the 20 filing records displayed, 12 carry bearish classifications (such as insider sales or negative 8-K disclosures) versus 1 bullish. This does not necessarily signal fundamental deterioration — insiders sell for many reasons — but it is worth monitoring alongside the company's core financial metrics.
DYN Filing Activity Snapshot 2026-08-13 — 2026-10-06
Insider Transactions (Form 4)
1 buy vs 8 sells
Net insider selling in this period — insiders sell for many reasons beyond conviction.
Largest Form 144 Filing
$65.18M
Rhodes Jason P (Director) · 2026-08-17
2,586,928 shares · Form 4
Form 144 Notices
10
Proposed insider sales filed — Form 144 is a notice of intent, not a confirmed transaction. Actual sales are confirmed via Form 4.
Insider Transactions 9 · Forms 3, 4 and 5

A Form 4 is filed within two business days of a company insider — an officer, a director, or a holder of more than ten percent of the stock — changing their position in the shares. All 9 filings in this group are Form 4s for Dyne Therapeutics, Inc.

The difficulty with reading these filings as a group is that a single form type covers transactions that mean entirely different things. An executive spending their own money to buy stock and an executive having shares withheld to pay tax on a vesting grant both appear as a Form 4. Every filing below is therefore tagged with the nature of the underlying transaction, taken from the transaction code reported on the form itself.

Across the 9 insider filings shown, the breakdown is 8 open-market sale and 1 open-market purchase. 9 of them involved a discretionary open-market trade; the rest are compensation and administrative mechanics.

What each transaction type means

Open-market sale ×8
The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.
Open-market purchase ×1
The insider bought shares on the open market with their own money. This is the only Form 4 category that requires a discretionary cash outlay at the prevailing price.
Form 4 Open-market purchase Insider Buying 2026-10-06

DYN insider Posner Brian S (Director) bought 2,500 shares (~$40.0K)

Posner Brian S, listed as Director at Dyne Therapeutics, Inc., reported an open-market purchase of 2,500 DYN shares in a Form 4 filing. Insider buying is often treated as a bullish signal because company insiders are committing their own capital.

The insider bought shares on the open market with their own money. This is the only Form 4 category that requires a discretionary cash outlay at the prevailing price.

Transactions reported on this filing
Code Nature Shares Price Value
P Open-market purchase 2,500 $16.00 $40.0K
Filing: Form 4 (Insider Transaction) Insider: Posner Brian S (Director) Shares: 2,500 Est. Value: $40.0K
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-09-08

DYN insider Friedl-Naderer Johanna (Chief Commercial Officer) sold 1,085 shares (~$25.4K)

Friedl-Naderer Johanna, listed as Chief Commercial Officer at Dyne Therapeutics, Inc., reported an open-market sale of 1,085 DYN shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 900 $24.35 $21.9K
S Open-market sale 185 $18.88 $3.5K
Filing: Form 4 (Insider Transaction) Insider: Friedl-Naderer Johanna (Chief Commercial Officer) Shares: 1,085 Est. Value: $25.4K
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-09-08

DYN insider Kerr Douglas (Chief Medical Officer) sold 5,035 shares (~$115.5K)

Kerr Douglas, listed as Chief Medical Officer at Dyne Therapeutics, Inc., reported an open-market sale of 5,035 DYN shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 3,745 $24.35 $91.2K
S Open-market sale 1,290 $18.88 $24.4K
Filing: Form 4 (Insider Transaction) Insider: Kerr Douglas (Chief Medical Officer) Shares: 5,035 Est. Value: $115.5K
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-09-08

DYN insider Cox John (Director, CEO & President) sold 5,658 shares (~$106.8K)

Cox John, listed as Director, CEO & President at Dyne Therapeutics, Inc., reported an open-market sale of 5,658 DYN shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 5,658 $18.88 $106.8K
Filing: Form 4 (Insider Transaction) Insider: Cox John (Director, CEO & President) Shares: 5,658 Est. Value: $106.8K
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-08-17

DYN insider Rhodes Jason P (Director) sold 2,586,928 shares (~$65.18M)

Rhodes Jason P, listed as Director at Dyne Therapeutics, Inc., reported an open-market sale of 2,586,928 DYN shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 268,354 $26.20 $7.03M
S Open-market sale 94,415 $26.20 $2.47M
S Open-market sale 63,643 $26.20 $1.67M
S Open-market sale 1,359,674 $25.00 $33.99M
S Open-market sale 478,377 $25.00 $11.96M
S Open-market sale 322,465 $25.00 $8.06M
Filing: Form 4 (Insider Transaction) Insider: Rhodes Jason P (Director) Shares: 2,586,928 Est. Value: $65.18M
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-08-17

DYN insider Friedl-Naderer Johanna (Chief Commercial Officer) sold 226 shares (~$5.9K)

Friedl-Naderer Johanna, listed as Chief Commercial Officer at Dyne Therapeutics, Inc., reported an open-market sale of 226 DYN shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 226 $26.28 $5.9K
Filing: Form 4 (Insider Transaction) Insider: Friedl-Naderer Johanna (Chief Commercial Officer) Shares: 226 Est. Value: $5.9K
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-08-17

DYN insider Kerr Douglas (Chief Medical Officer) sold 1,556 shares (~$40.9K)

Kerr Douglas, listed as Chief Medical Officer at Dyne Therapeutics, Inc., reported an open-market sale of 1,556 DYN shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 1,556 $26.28 $40.9K
Filing: Form 4 (Insider Transaction) Insider: Kerr Douglas (Chief Medical Officer) Shares: 1,556 Est. Value: $40.9K
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-08-17

DYN insider Cox John (Director, CEO & President) sold 4,986 shares (~$131.0K)

Cox John, listed as Director, CEO & President at Dyne Therapeutics, Inc., reported an open-market sale of 4,986 DYN shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 4,986 $26.28 $131.0K
Filing: Form 4 (Insider Transaction) Insider: Cox John (Director, CEO & President) Shares: 4,986 Est. Value: $131.0K
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-08-17

DYN insider Lucera Erick (Chief Financial Officer) sold 1,797 shares (~$47.2K)

Lucera Erick, listed as Chief Financial Officer at Dyne Therapeutics, Inc., reported an open-market sale of 1,797 DYN shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 1,797 $26.28 $47.2K
Filing: Form 4 (Insider Transaction) Insider: Lucera Erick (Chief Financial Officer) Shares: 1,797 Est. Value: $47.2K
View on SEC EDGAR → Open Filing Document →
Proposed Insider Sales 10 · Form 144

A Form 144 is a notice of intent to sell restricted or control securities. It is not a record that anything was sold. Dyne Therapeutics, Inc. has 10 such notices in this period.

The distinction matters because a Form 144 is frequently reported as though it were a completed insider sale. The filer may sell all of the shares covered, some of them, or none at all, and there is no obligation to update the notice either way. A sale that is actually executed by an officer or director shows up separately on a Form 4, which is the filing to check before treating a proposed sale as a real one.

Form 144 Proposed Insider Sale 2026-09-08

DYN Form 144 filed for proposed insider sale by Cox John (5,658 shares) ~$106.8K

Cox John filed a Form 144 with the SEC indicating intent to sell DYN (Dyne Therapeutics, Inc.) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: Cox John Shares: 5,658 Est. Value: $106.8K
View on SEC EDGAR → Open Filing Document →
Form 144 Proposed Insider Sale 2026-09-08

DYN Form 144 filed for proposed insider sale by Kerr Douglas (35 shares) ~$661.00

Kerr Douglas filed a Form 144 with the SEC indicating intent to sell DYN (Dyne Therapeutics, Inc.) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: Kerr Douglas Shares: 35 Est. Value: $661.00
View on SEC EDGAR → Open Filing Document →
Form 144 Proposed Insider Sale 2026-09-04

DYN Form 144 filed for proposed insider sale by Kerr Douglas (5,000 shares) ~$121.7K

Kerr Douglas filed a Form 144 with the SEC indicating intent to sell DYN (Dyne Therapeutics, Inc.) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: Kerr Douglas Shares: 5,000 Est. Value: $121.7K
View on SEC EDGAR → Open Filing Document →
Form 144 Large Proposed Insider Sale 2026-08-14

DYN Form 144 filed for proposed insider sale by Atlas Venture Opportunity Fund I, LP (322,465 shares) ~$8.37M

Atlas Venture Opportunity Fund I, LP filed a Form 144 with the SEC indicating intent to sell DYN (Dyne Therapeutics, Inc.) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4. The proposed dollar value is large enough to merit attention.

Filing: Form 144 (Proposed Sale Notice) Insider: Atlas Venture Opportunity Fund I, LP Shares: 322,465 Est. Value: $8.37M
View on SEC EDGAR → Open Filing Document →
Form 144 Large Proposed Insider Sale 2026-08-14

DYN Form 144 filed for proposed insider sale by Atlas Venture Fund XI, LP (1,359,674 shares) ~$35.30M

Atlas Venture Fund XI, LP filed a Form 144 with the SEC indicating intent to sell DYN (Dyne Therapeutics, Inc.) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4. The proposed dollar value is large enough to merit attention.

Filing: Form 144 (Proposed Sale Notice) Insider: Atlas Venture Fund XI, LP Shares: 1,359,674 Est. Value: $35.30M
View on SEC EDGAR → Open Filing Document →
Form 144 Large Proposed Insider Sale 2026-08-14

DYN Form 144 filed for proposed insider sale by Atlas Venture Opportunity Fund II, LP (478,377 shares) ~$12.42M

Atlas Venture Opportunity Fund II, LP filed a Form 144 with the SEC indicating intent to sell DYN (Dyne Therapeutics, Inc.) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4. The proposed dollar value is large enough to merit attention.

Filing: Form 144 (Proposed Sale Notice) Insider: Atlas Venture Opportunity Fund II, LP Shares: 478,377 Est. Value: $12.42M
View on SEC EDGAR → Open Filing Document →
Form 144 Proposed Insider Sale 2026-08-13

DYN Form 144 filed for proposed insider sale by Atlas Venture Opportunity Fund II, LP (94,415 shares) ~$2.47M

Atlas Venture Opportunity Fund II, LP filed a Form 144 with the SEC indicating intent to sell DYN (Dyne Therapeutics, Inc.) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: Atlas Venture Opportunity Fund II, LP Shares: 94,415 Est. Value: $2.47M
View on SEC EDGAR → Open Filing Document →
Form 144 Large Proposed Insider Sale 2026-08-13

DYN Form 144 filed for proposed insider sale by Atlas Venture Fund XI, LP (268,354 shares) ~$7.02M

Atlas Venture Fund XI, LP filed a Form 144 with the SEC indicating intent to sell DYN (Dyne Therapeutics, Inc.) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4. The proposed dollar value is large enough to merit attention.

Filing: Form 144 (Proposed Sale Notice) Insider: Atlas Venture Fund XI, LP Shares: 268,354 Est. Value: $7.02M
View on SEC EDGAR → Open Filing Document →
Form 144 Proposed Insider Sale 2026-08-13

DYN Form 144 filed for proposed insider sale by Atlas Venture Opportunity Fund I, LP (63,643 shares) ~$1.67M

Atlas Venture Opportunity Fund I, LP filed a Form 144 with the SEC indicating intent to sell DYN (Dyne Therapeutics, Inc.) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: Atlas Venture Opportunity Fund I, LP Shares: 63,643 Est. Value: $1.67M
View on SEC EDGAR → Open Filing Document →
Form 144 Proposed Insider Sale 2026-08-13

DYN Form 144 filed for proposed insider sale by Cox John (4,986 shares) ~$131.0K

Cox John filed a Form 144 with the SEC indicating intent to sell DYN (Dyne Therapeutics, Inc.) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: Cox John Shares: 4,986 Est. Value: $131.0K
View on SEC EDGAR → Open Filing Document →
Material Events 1 · Form 8-K

An 8-K reports a material event in the window between scheduled reports. There is 1 in this period for Dyne Therapeutics, Inc. Each 8-K names the item number it is filed under, and that number is the fastest way to tell a routine disclosure from a consequential one.

Item 2.02 is an earnings release, Item 5.02 is a change of directors or officers, and Item 1.01 or 2.01 covers a material agreement or a completed acquisition. Item 7.01 and Item 8.01 are the general-purpose disclosure items and carry no fixed meaning on their own.

Form 8-K Material Company Update 2026-09-29

DYN filed 8-K — material company event

Dyne Therapeutics, Inc. filed an 8-K with the SEC reporting a material event. Summary unavailable — view the original SEC filing for the full text.

Filing: 8-K (Material Event)
View on SEC EDGAR → Open Filing Document →

How we classify Dyne Therapeutics, Inc.'s filings

Straight from EDGAR

Each displayed record links to an original source document. StrongBuyAnalytics provides navigation and brief excerpts or summaries, not the filing itself. Parsing may omit context or contain errors, so read the original document in full.

Transaction codes, not guesswork

The nature shown on each insider filing comes from the transaction code the filer entered on the form itself — P for an open-market purchase, A for a compensation award, F for shares withheld to pay tax, M for an option exercise. Where one filing contains several codes, the transaction table lists them line by line.

Why the distinction matters

Insider activity is routinely summarised as buying or selling, which flattens together decisions that mean very different things. Shares withheld for tax on a vesting grant are an automatic administrative step; shares bought on the open market are someone committing their own money at the current price.

What this page does not tell you

A filing records what happened, not why. Form 4 does not always disclose whether a sale was executed under a pre-arranged Rule 10b5-1 plan, and no single filing is a basis for a decision on DYN. Read these alongside the fundamentals rather than in isolation.

Frequently Asked Questions — DYN SEC Filings

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Publisher, sources & limitations — September 15, 2026. StrongBuyAnalytics provides navigation and brief excerpts or summaries for educational use. Original filings remain at SEC EDGAR or other displayed source links; StrongBuyAnalytics does not author them. Filing dates are source dates, not publication dates for this page. Coverage can be delayed, incomplete, amended, or unavailable because of SEC/source availability, parsing, caching, or outages. Verify every material statement in the original filing.
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