Final answer:
Carnegie and Morgan agreed on a price of $500 million initially, but the resulting U.S. Steel Corporation was valued at $1.4 billion.
Step-by-step explanation:
Andrew Carnegie and J.P. Morgan agreed on a price of $500 million. However, after the consolidation of Carnegie's holdings with other smaller steel firms, the resulting company, U.S. Steel Corporation, was subsequently capitalized at $1.4 billion. This made it the first billion-dollar firm in the United States.