Perhaps not surprisingly, the symbol of power for the age was not an industrialist, but the financier J. P. Morgan. Huge financial resources were needed to fund huge companies, and often those in charge of the banks became rulers over the new empires. Morgan had twice been instrumental in national efforts to recover from or avert financial panics, first in 1893 and again in 1907. Moreover, "the House of Morgan," as the banking firm of J. P. Morgan and Company was known, played a crucial role in the reorganization of the nation's railroads. Morgan himself became the effective head of the most gargantuan of the new "trusts" - U.S. Steel Corporation, which controlled more than 60 percent of all American production of that critical metal.
Faced with this concentration of power, Americans grew increasingly ambivalent about the cost of the prosperity and efficiency that big corporations promised.
(National Geographic: ‘The 20th Century’)