PROTOPAPAS ANNA (President & CEO) reported 3 transactions at MERSANA THERAPEUTICS, INC.

Review the transaction codes below to understand the nature of each event.

PROTOPAPAS ANNA

Filed: 1/6/2026ACC: 0001104659-26-001374

InsiderPROTOPAPAS ANNACIK 1347582

→

IssuerMERSANA THERAPEUTICS, INC.CIK 1442836

DirectorOfficer· President & CEO

Since Jan 2019

-83.31K

Net shares

Net seller

$0.00

Total acquired

Open market trades

0B · 0S

Total transactions

83.31K disposed

Non-Derivative Transactions3

Common Stock

Direct

U · U

−6.72K

Price / share

—

Trade value

—

% of position

New position

1/6/2026

6.72K→0.00

Common Stock

Indirect

U · U

−2.89K

Price / share

—

Trade value

—

% of position

New position

1/6/2026

2.89K→0.00

Common Stock

Indirect

U · U

−9.61K

Price / share

—

Trade value

—

% of position

New position

1/6/2026

9.61K→0.00

Total

Net shares

−19.22K

Net value

$0.00

Security	Date	Type	Shares	Price / Share	Trade Value	% of Position	Held Before	Held After
Common Stock Direct	1/6/2026	U · U	−6.72K	—	—	New position	6.72K	0.00
Common Stock Indirect	1/6/2026	U · U	−2.89K	—	—	New position	2.89K	0.00
Common Stock Indirect	1/6/2026	U · U	−9.61K	—	—	New position	9.61K	0.00
Total			−19.22K		$0.00

Derivative Transactions17

Stock Option (right to buy)

Direct

D · Disposition

Converts to

Common Stock

2.46K shares

−2.46K

Strike price

9.0775

Held after

0.00

Exercisable

—

1/6/2026

Stock Option (right to buy)

Direct

D · Disposition

Converts to

Common Stock

2.50K shares

−2.50K

Strike price

174.50

Held after

0.00

Exercisable

—

1/6/2026

Stock Option (right to buy)

Direct

D · Disposition

Converts to

Common Stock

480.00 shares

−480.00

Strike price

355.75

Held after

0.00

Exercisable

—

1/6/2026

Stock Option (right to buy)

Direct

D · Disposition

Converts to

Common Stock

7.52K shares

−7.52K

Strike price

355.75

Held after

0.00

Exercisable

—

1/6/2026

Stock Option (right to buy)

Direct

D · Disposition

Converts to

Common Stock

542.00 shares

−542.00

Strike price

87.75

Held after

0.00

Exercisable

—

1/6/2026

Stock Option (right to buy)

Direct

D · Disposition

Converts to

Common Stock

8.14K shares

−8.14K

Strike price

87.75

Held after

0.00

Exercisable

—

1/6/2026

Stock Option (right to buy)

Direct

D · Disposition

Converts to

Common Stock

1.00 shares

−1.00

Strike price

87.75

Held after

0.00

Exercisable

—

1/6/2026

Stock Option (right to buy)

Direct

D · Disposition

Converts to

Common Stock

18.00 shares

−18.00

Strike price

87.75

Held after

0.00

Exercisable

—

1/6/2026

Stock Option (right to buy)

Direct

D · Disposition

Converts to

Common Stock

988.00 shares

−988.00

Strike price

154.00

Held after

0.00

Exercisable

—

1/6/2026

Stock Option (right to buy)

Direct

D · Disposition

Converts to

Common Stock

11.76K shares

−11.76K

Strike price

154.00

Held after

0.00

Exercisable

—

1/6/2026

Stock Option (right to buy)

Direct

D · Disposition

Converts to

Common Stock

665.00 shares

−665.00

Strike price

33.00

Held after

0.00

Exercisable

—

1/6/2026

Stock Option (right to buy)

Direct

D · Disposition

Converts to

Common Stock

9.04K shares

−9.04K

Strike price

157.00

Held after

0.00

Exercisable

—

1/6/2026

Stock Option (right to buy)

Direct

D · Disposition

Converts to

Common Stock

11.25K shares

−11.25K

Strike price

151.50

Held after

0.00

Exercisable

—

1/6/2026

Stock Option (right to buy)

Direct

D · Disposition

Converts to

Common Stock

2.20K shares

−2.20K

Strike price

56.50

Held after

0.00

Exercisable

—

1/6/2026

Stock Option (right to buy)

Direct

D · Disposition

Converts to

Common Stock

1.13K shares

−1.13K

Strike price

102.50

Held after

0.00

Exercisable

—

1/6/2026

Stock Option (right to buy)

Direct

D · Disposition

Converts to

Common Stock

5.23K shares

−5.23K

Strike price

102.50

Held after

0.00

Exercisable

—

1/6/2026

Stock Option (right to buy)

Direct

D · Disposition

Converts to

Common Stock

166.00 shares

−166.00

Strike price

174.50

Held after

0.00

Exercisable

—

1/6/2026

Security	Converts To	Date	Type	Shares	Strike Price	Exercisable
Stock Option (right to buy) Direct	Common Stock2.46K shares	1/6/2026	D · Disposition	−2.46K	9.0775	—
Stock Option (right to buy) Direct	Common Stock2.50K shares	1/6/2026	D · Disposition	−2.50K	174.50	—
Stock Option (right to buy) Direct	Common Stock480.00 shares	1/6/2026	D · Disposition	−480.00	355.75	—
Stock Option (right to buy) Direct	Common Stock7.52K shares	1/6/2026	D · Disposition	−7.52K	355.75	—
Stock Option (right to buy) Direct	Common Stock542.00 shares	1/6/2026	D · Disposition	−542.00	87.75	—
Stock Option (right to buy) Direct	Common Stock8.14K shares	1/6/2026	D · Disposition	−8.14K	87.75	—
Stock Option (right to buy) Direct	Common Stock1.00 shares	1/6/2026	D · Disposition	−1.00	87.75	—
Stock Option (right to buy) Direct	Common Stock18.00 shares	1/6/2026	D · Disposition	−18.00	87.75	—
Stock Option (right to buy) Direct	Common Stock988.00 shares	1/6/2026	D · Disposition	−988.00	154.00	—
Stock Option (right to buy) Direct	Common Stock11.76K shares	1/6/2026	D · Disposition	−11.76K	154.00	—
Stock Option (right to buy) Direct	Common Stock665.00 shares	1/6/2026	D · Disposition	−665.00	33.00	—
Stock Option (right to buy) Direct	Common Stock9.04K shares	1/6/2026	D · Disposition	−9.04K	157.00	—
Stock Option (right to buy) Direct	Common Stock11.25K shares	1/6/2026	D · Disposition	−11.25K	151.50	—
Stock Option (right to buy) Direct	Common Stock2.20K shares	1/6/2026	D · Disposition	−2.20K	56.50	—
Stock Option (right to buy) Direct	Common Stock1.13K shares	1/6/2026	D · Disposition	−1.13K	102.50	—
Stock Option (right to buy) Direct	Common Stock5.23K shares	1/6/2026	D · Disposition	−5.23K	102.50	—
Stock Option (right to buy) Direct	Common Stock166.00 shares	1/6/2026	D · Disposition	−166.00	174.50	—