re: Corporate power
I don't have any reason to doubt your figures, and they are quite astonishing, half of the economy is controlled by 0.3% of the firms.
.3% of 25 million* is 75,000 businesses. And considering they all have have more 500 employess, that has to be +37.5 million people in involved- probably closer to +50 million. And though a business with a low number of employees over 500 employees are perhaps too small to be on the Stock Market, the larger companies with say +5,000 employees are going to be increasely publicly owned.
*"In 2004, there were approximately 24.7 million businesses
in the United States"
From Tom's link.