The host-guest challenge of SAMPL9 was organized similar to SAMPL7-8, where the main part of the challenge (for ranking) allows participants to submit a single method as a ranked submission for any or all of the datasets (WP6 and bCD / HbCD). For the main analysis of the challenge only ranked submissions were considered. Participants were encouraged to submit additional submissions, and any additional submissions were not included in formal ranking. A requirement for a submission for either dataset, regardless if ranked or non-ranked, was to include all guests. Participants formally submitted blind predictions to the relevant challenge submission server prior to the deadline. In addition, MA conducted blind reference calculations which were submitted in the non-ranked category. These provide a point of comparison with a previous literature method.