Berkshire Hathaway, the investment firm headed by billionaire investor Warren Buffett, has increased its stake in three blue-chip companies during the first quarter, according to a regulatory filing by the company.

Berkshire Hathaway has said in a filing that it increased its stake in banking giant Wells Fargo and it also added stake in American business icons such as computer maker IBM, one of his new bigger holdings, and retail behemoth Wal-Mart Stores. Berkshire decided to purchase additional shares of International Business Machines Corp. Wal-Mart Stores as an indication that the US economy might be recovering.

The $85 billion stock portfolio made a few changes during the quarter from January to March, 2013. It is believed that his buy-and-sell decisions offer a way forward to many investors on Wall Street. When his decisions are made public, the prices of the shares he owns generally rises, come thing referred to as the "Buffett Effect".

The investment firm unloaded stakes in Archer Daniels Midland and General Dynamics and also initiated a position in Chicago Bridge & Iron, it said in a 13F filing for the first quarter till March, 2013. The company has released its required 13F filing on Wednesday after the closing bell.