ROSENBLATT DAVID S (Chief Executive Officer) exercised options at 1STDIBS.COM, INC.

Option exercise — a mechanical event triggered by vesting or expiry. Not a discretionary conviction trade.

M · 3 exercises

ROSENBLATT DAVID S

Filed: 3/11/2026ACC: 0001237860-26-000004

InsiderROSENBLATT DAVID SCIK 1237860

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Issuer1STDIBS.COM, INC.CIK 1600641

DirectorOfficer· Chief Executive Officer

Since Jun 2021

-62.09K

Net shares

Net seller

$340.9K

Total sold

Open market trades

0B · 0S

Total transactions

132.50K acquired · 194.59K disposed

Non-Derivative Transactions4

Common Stock

Direct

M · Option Exercise

+37.50K

Price / share

—

Trade value

—

% of position

1.9%

3/9/2026

1.98M→2.01M

Common Stock

Direct

M · Option Exercise

+47.50K

Price / share

—

Trade value

—

% of position

2.4%

3/9/2026

2.01M→2.06M

Common Stock

Direct

M · Option Exercise

+47.50K

Price / share

—

Trade value

—

% of position

2.3%

3/9/2026

2.06M→2.11M

Common Stock

Direct

F · Tax Withholding

−62.09K

Price / share

$5.49

Trade value

$340.86K

% of position

2.9%

3/9/2026

2.11M→2.05M

Total

Net shares

+70.41K

Net value

-$340.86K

Security	Date	Type	Shares	Price / Share	Trade Value	% of Position	Held Before	Held After
Common Stock Direct	3/9/2026	M · Option Exercise	+37.50K	—	—	1.9%	1.98M	2.01M
Common Stock Direct	3/9/2026	M · Option Exercise	+47.50K	—	—	2.4%	2.01M	2.06M
Common Stock Direct	3/9/2026	M · Option Exercise	+47.50K	—	—	2.3%	2.06M	2.11M
Common Stock Direct	3/9/2026	F · Tax Withholding	−62.09K	$5.49	$340.86K	2.9%	2.11M	2.05M
Total			+70.41K		-$340.86K

Derivative Transactions3

Restricted Stock Units

Direct

M · Option Exercise

Converts to

Common Stock

37.50K shares

−37.50K

Strike price

Held after

150K

Exercisable

—

3/9/2026

Restricted Stock Units

Direct

M · Option Exercise

Converts to

Common Stock

47.50K shares

−47.50K

Strike price

Held after

380K

Exercisable

—

3/9/2026

Restricted Stock Units

Direct

M · Option Exercise

Converts to

Common Stock

47.50K shares

−47.50K

Strike price

Held after

570K

Exercisable

—

3/9/2026

Security	Converts To	Date	Type	Shares	Exercisable	Held After
Restricted Stock Units Direct	Common Stock37.50K shares	3/9/2026	M · Option Exercise	−37.50K	—	150K
Restricted Stock Units Direct	Common Stock47.50K shares	3/9/2026	M · Option Exercise	−47.50K	—	380K
Restricted Stock Units Direct	Common Stock47.50K shares	3/9/2026	M · Option Exercise	−47.50K	—	570K

Non-Derivative Holdings (Post-Transaction)2

Common Stock

Indirect

Shares owned665.30K

Common Stock

Indirect

Shares owned22.50K

Total

687.80K indirect687.80K

Security Title	Shares Owned	Ownership Type
Common Stock	665.30K	Indirect
Common Stock	22.50K	Indirect
Total	687.80K	687.80K indirect

Derivative Holdings (Post-Transaction)0

No derivative holdings reported