Buffett's Berkshire Hathaway joins S&P500

Millions of Americans will now own a little piece of Warren Buffett's Berkshire Hathaway after the company listed on the S&P500 after trading closed on Wall Street last week.

Berkshire, the $176bn (£112bn) conglomerate run by Buffett for 45 years, enters the index following the $26.3bn acquisition of railway operator Burlington Northern Santa Fe, the Telegraph reports.

As a result, $1trn of consumer-backed index funds have been forced to buy stakes in Berkshire.

It is estimated the funds would have to buy an estimated 150m-175m shares of Berkshire's class B shares worth $11.3bn to $13.2bn in order to ensure the correct weighting of Berkshire in their funds.

Berkshire B shares, often known as the 'Baby Berks', have risen from $68 in late January to $76.90 in late trading on Friday.

However, the American public's increased exposure to Berkshire follows the conglomerate's recent loss of its Triple-A credit rating amid concerns about its debt position, according to the Telegraph.