Line Stretching - Occurs when company lengthens its product line beyond its current range.
Downward stretching –High market position company introduces new products into their line of products at lower price for low end segment.
E.g. BMW car company is known as a car for high end segment add a new eco-car model at cheaper price for low end customers.
Upward stretching –Low position company stretches their product line upward by offering new products that come in high price for high end segment.
E.g. Toyota is usually known as a car company for medium segment. Few years ago , Toyota stretched upward by launching Lexus for Upper automobile market.