Cardio Diagnostics Holdings is trading at $2.00, up 6.95%, with no clear company-specific catalyst identified for its October 9 after-hours rise. - The latest surfaced company announcement was dated August 26. - Broader U.S. stocks rose October 9: the S&P 500 gained 0.61% and the Dow 0.95%, which may have supported sentiment. - The regular-session close was $1.87, after a 0.54% gain that session.