Short-period giant planets are frequently found to be solitary compared to other classes of exoplanets. Small inner companions to giant planets with P \lesssim 15 days are known only in five compact systems: WASP-47, Kepler-730, WASP-132, TOI-1130, and TOI-2000. Here, we report the confirmation of TOI-5398, the youngest compact multi-planet... Show more