What happens if a runner loses possession during a run?

When a runner loses possession of the ball during a run, the run indeed is considered to have ended at the spot where possession was lost. This means that any yards gained prior to the loss of possession count towards the runner's statistics for that play. The officials will mark the ball at the spot of the fumble, and the team that had possession will retain the down, except in scenarios where the ball is fundamentally turned over, such as a fumble being recovered by the opposing team.

This understanding aligns with the rules regarding possession in a football game: a runner can gain yards until they lose control of the ball. As a result, the team retains the rights to the down, and any yardage gained up to the point of the loss is acknowledged in the play statistics.

In other scenarios, if the ball is turned over or the run is replayed, this would imply a different context, such as a fumble being recovered by the opposing team or a penalty situation that mandates a replay of the down. However, in the specific case of simply losing possession through a fumble without the defense recovering the ball, the play ends at the spot of the loss, making this answer accurate.