Why did Blue Ocean manually halt a symbol?
Manual halts are applied on a case-by-case basis.
Blue Ocean may manually halt a symbol on a case-by-case basis to ensure compliance with fair access requirements. For example, YINN and YANG were halted earlier this year because trading activity reached the fair access thresholds. The SEC outlines these thresholds in its fair access guidance.
Manual halts are always communicated to participants. Notices are sent before each session in the daily halt email, published in the halts file on the SFTP site, and archived under Service Alerts and Announcements.