By Ellen Chang Berkshire Hathaway increased stake of Activision is nearly 10%. Berkshire Hathaway ( (BRK.A) – Get Berkshire Hathaway Inc. Class A Report) CEO Warren Buffett revealed the conglomerate owns a 9.5% stake of Activision Blizzard ( (ATVI) – Get Activision Blizzard, Inc. Report) from its initial stake of 2%, the gaming company, that is set to be acquired by Microsoft ( (MSFT) – Get Microsoft Corporation Report). “If the deal goes through, we make some money,” he said at the company’s annual shareholder meeting. Buffett said the purchase of additional shares was his decision. A majorit…