We report the discovery of activity on asteroid 6993 (1995 BJ4) in the Zwicky Transient Facility (ZTF) alert stream data on UT 2026 August 5, with the help of machine learning. Visible activity can be seen as early as UT 2026 June 25. Activity on this outer-main belt object is likely not primarily driven by rotational instability, but rather is consistent with an impact event or sublimation based on several arguments. If this activity is sublimation driven, 6993 would be the largest known main belt comet (11.85 km), with the largest perihelion distance (2.853 au) and an unusually high geometric albedo of 0.166 $\pm$ 0.030. Asteroid 6993 should be monitored as it approaches perihelion in 2027 January to distinguish between activity mechanisms and understand its potential volatile inventory.