Benefit plans	6 Months Ended
Jun. 30, 2019
Benefit plans
Benefit plans	14. Benefit plans The Company established a defined‑contribution savings plan under Section 401(k) of the United States Internal Revenue Code (the “401(k) Plan”). The 401(k) Plan covers all U.S. employees and allows participants to defer a portion of their annual compensation on a pre‑tax basis. Matching contributions to the 401(k) Plan may be made at the discretion of the Company’s board of directors. During the three months ended June 30, 2019 and 2018 the Company made contributions totaling $25,000 and $19,000, respectively, to the 401(k) Plan. During the six months ended June 30, 2019 and 2018, the Company made contributions totaling $0.1 million and $0.1 million, respectively, to the 401(k) Plan. The Company provides a pension contribution plan for its employees in the United Kingdom, pursuant to which the Company contributes each year amounts of up to 12% of their annual base salary (“U.K Plan”). During the three months ended June 30, 2019 and 2018, the Company made contributions totaling $0.1 million and $0.1 million, respectively, to the U.K. Plan. During the six months ended June 30, 2019 and 2018, the Company made contributions totaling $0.2 million and $0.1 million, respectively, to the U.K. Plan.

14. Benefit plans

The Company established a defined‑contribution savings plan under Section 401(k) of the United States Internal Revenue Code (the “401(k) Plan”). The 401(k) Plan covers all U.S. employees and allows participants to defer a portion of their annual compensation on a pre‑tax basis. Matching contributions to the 401(k) Plan may be made at the discretion of the Company’s board of directors. During the three months ended June 30, 2019 and 2018 the Company made contributions totaling $25,000 and $19,000, respectively, to the 401(k) Plan. During the six months ended June 30, 2019 and 2018, the Company made contributions totaling $0.1 million and $0.1 million, respectively, to the 401(k) Plan.

The Company provides a pension contribution plan for its employees in the United Kingdom, pursuant to which the Company contributes each year amounts of up to 12% of their annual base salary (“U.K Plan”). During the three months ended June 30, 2019 and 2018, the Company made contributions totaling $0.1 million and $0.1 million, respectively, to the U.K. Plan. During the six months ended June 30, 2019 and 2018, the Company made contributions totaling $0.2 million and $0.1 million, respectively, to the U.K. Plan.