That's an example of 'market penetration' strategic options.
M&S resorts to one-day sale move
Marks and Spencer is to hold a one-day, 20%-off sale on Thursday, a move that analysts see as a sign that the retailer is continuing to struggle.
The move will see M&S go head-to-head with Debenhams in an effort to entice customers after dismal October trading.
Read the whole article at: http://news.bbc.co.uk/1/hi/business/7737281.stm