There are currently 123 countries that ratified the Rome Statute, which recognizes the International Criminal Court's (ICC) jurisdiction to prosecute and judge genocide, war crimes and crimes against the humanity committed by nationals of the state parties or within their territories.

So far, only four state parties have notified their intention of withdrawing from the treaty, according to its Article 127: Burundi, Philippines, Gambia and South Africa. Gambia and South Africa eventually revoked their notifications, but withdrawal threats arise every now and then.

This market tries to quantify how many new withdrawal notifications will be deposited to the Secretary-General on or before December 31st, 2029, independently of them coming into effect or being revoked during this period of time. A country can fill more than one notification, if the previous one has been revoked.

Source for quick reference: https://en.wikipedia.org/wiki/States_parties_to_the_Rome_Statute_of_the_International_Criminal_Court

Authoritative source: https://treaties.un.org/Pages/ViewDetails.aspx?src=TREATY&mtdsg_no=XVIII-10&chapter=18&clang=_en#ctl00_ctl00_ContentPlaceHolder1_ContentPlaceHolderInnerPage_dgNotesAll_ctl03_divNotesAll