At the end of trading session on Monday, Buffett's net worth stood at USD 54.9 billion, while Ortega's market capitalisation stood at USD 54.5 billion.
"After Monday's markets closed, Ortega was down USD 2.5 billion from his net worth at the time we finalised our numbers for the 2013 Forbes billionaires list, which we published on March 4 using February 14, 2013 stock prices. Buffett, by contrast, was up USD 1.4 billion," Forbes said.
"Those are tiny shifts, but given the concentrated holdings each of the billionaires has in these companies, coupled with the constantly moving dollar-to-euro exchange rate, the changes were enough for the billionaires to flip- flop positions on the Forbes ranks," Forbes said.
As per the annual ranking published by Forbes on March 4, Mexican business tycoon Carlos Slim was the wealthiest in the world with a networth of USD 73 billion, followed by Bill Gates (USD 67 billion), Amancio Ortega (USD 57 billion), Warren Buffett (USD 53.5 billion).
According to the latest Forbes ranking Mukesh Ambani was ranked 22nd, while the second-richest Indian Lakshmi Mittal is at 41st position with a networth of USD 16.5 billion.