Offerings	Mar. 11, 2026 USD ($) shares
Offering: 1
Offering:
Fee Previously Paid	false
Other Rule	true
Security Type	Equity
Security Class Title	Common stock, no par value per share
Amount Registered \| shares	3,000,000
Proposed Maximum Offering Price per Unit	2.40
Maximum Aggregate Offering Price	$ 7,200,000.00
Fee Rate	0.01381%
Amount of Registration Fee	$ 994.32
Offering Note	Amount registered represents shares of the Registrant's common stock, no par value per share ("Common Stock"), reserved for issuance under the XBiotech Inc. 2025 Equity Incentive Plan (the "Plan") or underlying outstanding awards granted pursuant to the Plan. Pursuant to Rule 416(a) under the Securities Act of 1933, as amended (the "Securities Act"), this Registration Statement also covers any additional shares of Common Stock that may become issuable under the Plan by the Registrant by reason of certain corporate transactions or events, including any stock dividend, stock split, recapitalization or any other similar transaction effected without the receipt of consideration which results in an increase in the number of the Registrant's outstanding shares of common stock. The proposed maximum offering price per unit is estimated in accordance with Rules 457(c) and (h) of the Securities Act solely for the purpose of calculating the registration fee based on the average of the high and low prices of the Registrant's common stock as reported on the Nasdaq Stock Market on February 12th, 2026. The Registrant does not have any fee offsets.
Offering: 2
Offering:
Fee Previously Paid	false
Other Rule	true
Security Type	Equity
Security Class Title	Common stock, no par value per share
Amount Registered \| shares	5,382,681
Proposed Maximum Offering Price per Unit	2.40
Maximum Aggregate Offering Price	$ 12,918,434.40
Fee Rate	0.01381%
Amount of Registration Fee	$ 1,784.04
Offering Note	Amount registered represents shares of Common Stock that may become available for issuance under the Plan upon the forfeiture, cancelation or expiration of outstanding stock options granted under the XBiotech Inc. 2015 Equity Incentive Plan, as amended. Pursuant to Rule 416(a) under the Securities Act, this Registration Statement also covers any additional shares of Common Stock that may become issuable under the Plan by the Registrant by reason of certain corporate transactions or events, including any stock dividend, stock split, recapitalization or any other similar transaction effected without the receipt of consideration which results in an increase in the number of the Registrant's outstanding shares of common stock. The proposed maximum offering price per unit is estimated in accordance with Rules 457(c) and (h) of the Securities Act solely for the purpose of calculating the registration fee based on the average of the high and low prices of the Registrant's common stock as reported on the Nasdaq Stock Market on February 12th, 2026. The Registrant does not have any fee offsets.

Offerings

Mar. 11, 2026

USD ($)

Offering:

false

true

Equity

Common stock, no par value per share

Amount Registered | shares

3,000,000

Proposed Maximum Offering Price per Unit

2.40

Maximum Aggregate Offering Price

$ 7,200,000.00

Fee Rate

0.01381%

Amount of Registration Fee

$ 994.32

Offering Note

Amount registered represents shares of the Registrant's common stock, no par value per share ("Common Stock"), reserved for issuance under the XBiotech Inc. 2025 Equity Incentive Plan (the "Plan") or underlying outstanding awards granted pursuant to the Plan. Pursuant to Rule 416(a) under the Securities Act of 1933, as amended (the "Securities Act"), this Registration Statement also covers any additional shares of Common Stock that may become issuable under the Plan by the Registrant by reason of certain corporate transactions or events, including any stock dividend, stock split, recapitalization or any other similar transaction effected without the receipt of consideration which results in an increase in the number of the Registrant's outstanding shares of common stock. The proposed maximum offering price per unit is estimated in accordance with Rules 457(c) and (h) of the Securities Act solely for the purpose of calculating the registration fee based on the average of the high and low prices of the Registrant's common stock as reported on the Nasdaq Stock Market on February 12th, 2026. The Registrant does not have any fee offsets.

Offering:

false

true

Equity

Common stock, no par value per share

Amount Registered | shares

5,382,681

Proposed Maximum Offering Price per Unit

2.40

Maximum Aggregate Offering Price

$ 12,918,434.40

Fee Rate

0.01381%

Amount of Registration Fee

$ 1,784.04

Offering Note

Amount registered represents shares of Common Stock that may become available for issuance under the Plan upon the forfeiture, cancelation or expiration of outstanding stock options granted under the XBiotech Inc. 2015 Equity Incentive Plan, as amended. Pursuant to Rule 416(a) under the Securities Act, this Registration Statement also covers any additional shares of Common Stock that may become issuable under the Plan by the Registrant by reason of certain corporate transactions or events, including any stock dividend, stock split, recapitalization or any other similar transaction effected without the receipt of consideration which results in an increase in the number of the Registrant's outstanding shares of common stock. The proposed maximum offering price per unit is estimated in accordance with Rules 457(c) and (h) of the Securities Act solely for the purpose of calculating the registration fee based on the average of the high and low prices of the Registrant's common stock as reported on the Nasdaq Stock Market on February 12th, 2026. The Registrant does not have any fee offsets.