mark up vs undersell

mark up

verb
  • To increase the price of something between its wholesale and retail phase. 

  • To add coding to text so that it will display properly on a computer. 

undersell

verb
  • To sell goods for a lower price than a competitor. 

  • To sell something for less than its value. 

  • To put forward an idea, or to market a new product, with insufficient enthusiasm. 

How often have the words mark up and undersell occurred in a corpus of books? (source: Google Ngram Viewer )