has it invested in any other firms?
Yes, Apple Inc., is one of them.
Berkshire Hathaway
In May 2016, it was revealed in a regulatory filing that Berkshire had acquired a stake in Apple Inc. 
where was microsoft founded and who founded them It was founded by Bill Gates and Paul Allen in Albuquerque, New Mexico. what products do they make? It develops, manufactures, licenses, supports, and sells computer software, consumer electronics, personal computers, and related services. who is the first founder mentioned? He is an American business magnate, software developer, and philanthropist. where was he born? Seattle, Washington what did he start his career as? UNANSWERABLE was he associated with any other renowned company? Yes, IBM. what does it stand for? International Business Machines Corporation where is it headquartered in? Armonk, New York does it do any type of research? Yes, they constitute to the largest industrial research organization in the world, with 12 labs on 6 continents. what service does it provide? Their services fall into the categories of cloud computing, Artificial intelligence, commerce, data and analytics, Internet of Things (IoT), IT infrastructure, mobile, Digital workplace and security. who are it's shareholders? Warren Buffett's holding company Berkshire Hathaway was one of them. what is the last mentioned company about? It s an American multinational conglomerate holding company. who governs it? The current members of the board of directors Warren Buffett, Charlie Munger, Walter Scott, Jr., Thomas S. Murphy, Howard Graham Buffett  and Ronald Olson to name a few.
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Berkshire Hathaway [SEP] Investment in Apple Inc
In May 2016, it was revealed in a regulatory filing that Berkshire had acquired a stake in Apple Inc. The initial position was for 9.8 million shares (0.2% of Apple) worth $1 billion. By the end of June 2016, this stake had increased to 15.2 million shares (0.3% of Apple). Berkshire then restarted buying Apple stock again between September to December. By December 31, 2016, Berkshire had built up a stake of 57.4 million shares (1.1% of Apple) with an estimated average acquisition price of $110 per share. Aggressive stock purchases continued and by March 31, 2017, Berkshire had amassed a stake of 129 million shares (2.5% of Apple).