I did not know that...is it possible?

One of the half dozen or so books I am either reading or ristening to is Almost America (From the Colonists to Clinton: a "What if" History of the US by Steve Tally. In it there is something I learned that will no doubt work its way into class that was surprising to me:

From P 187

"In the late 1800s, American business was caught up in a frenzy of mergers. Across the country, small local businesses were selling out to large national trusts--from 1897 to 1904, one third of the companies in the United States were absorbed into larger companies. Consumers were not the beneficiaries of these mergers, however: Prices on goods inceased as much as 400 percent after competition was knocked out."

Which deserves a "wow". Not because there was a large merger wave, I think most knew that, but the enormous size of the wave. Can that possible be correct? Maybe tomorrow I will look at inflation over that period. I am sure it will take about 30 seconds, but I am tired now. I will just update this here and not do a new entry.