IBM could completely paralyze the entire computer industry with their portfolio. That they don't is a testament to how much money they earn in simply letting others do the "hard" PC stuff while they singularly engulf the big iron market.
IBM was the only company that I know of that actually outlasted the US government in antitrust litigation. The DoJ, after 15 YEARS of litigation, simply dropped the case due to lack of will and resources to continue. Oracle wouldn't dare try IBM in court.