initials vs trademark

initials

noun
  • An abbreviation of a person's name, constructed by taking the initial letters of first, last, and sometimes middle name(s). See monogram 

trademark

noun
  • A word, symbol, or phrase used to identify a particular company's product and differentiate it from other companies' products. 

  • Any proprietary business, product or service name. 

  • The aspect for which someone or something is best known; a hallmark or typical characteristic. 

adj
  • Distinctive, characteristic, signature. 

verb
  • To register something as a trademark. 

  • To so label a product. 

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