Armada Acquisition Corp. II (XRPN) shares were down more than 16% in premarket activity Tuesday following a nearly 2% fall in the prior session.

HeartSciences (HSCS) stock was 14% lower after a 1.4% gain in the prior session.

WISeSat.Space (SAIQ) shares were down 13% after a 260% rise at the previous close.

CTW (CTW) stock was 7% lower after remaining flat at Monday's close.

Republic Power Group (RPGL) shares were down 4% after a regulatory filing showed that the company and its institutional investor mutually agreed to terminate an additional investment right, with Republic paying a $250,000 termination fee.