This story has been updated to include analysis from an M&A expert.
Nutrisystem Inc.'s shares soared Monday morning after news broke of its upcoming acquisition by Tennessee-based Tivity Health Inc., the shares of which took a tumble.
Fort Washington, Pa.-based Nutrisystem and Franklin, Tenn.-based Tivity Health on Monday announced a $1.3 billion deal in which the weight-management company would sell to the health company known for fitness program SilverSneakers.
