Margin collection timing updated: continuous use of risk parameter files and additional snapshot verification for extended trading hours. The circular withdraws the prior 5:00 PM cut-off for determining client margin thresholds, directing clearing corporations to use Risk Parameter Files to generate margin obligations throughout trading hours. Clearing corporations must send additional snapshots-minimum two for contracts traded until later evening and minimum three for contracts traded into the night-with margins and end-of-day margins determined as per the relevant RPFs.