IBM has always been in IT:

  The company was founded in 1911 as the Computing
  Tabulating Recording Corporation through a merger of four
  companies: the Tabulating Machine Company, the   
  International Time Recording Company, the Computing Scale 
  Corporation, and the Bundy Manufacturing Company.

  http://en.wikipedia.org/wiki/IBM

The reason why IBM still exists to this day while most of its competitors have vanished is because they have been able to redefine what IT means for IBM. That and some of the world's best managers.

I suppose an IBM stockholder from 100 years ago to now might disagree about how they have nothing in common.

"A corporation is an artificial being, invisible, intangible and exiting only in contemplation of law. It has neither mind nor body of its own."

The metaphor I've always liked is: a pile of money that hires people to make itself bigger.