Below, you'll learn why Buffett decided to add HP (NYSE: HPQ) to the Berkshire portfolio, and then you'll see which other stock got good news on Thursday morning. Big uncertainties about exactly how the Federal Reserve will handle interest rates to fight inflation are giving investors headaches, but at least on Thursday morning, it appeared that market participants would get a reprieve from the volatility. The move followed filings from Berkshire Hathaway with the U.S. Securities and Exchange Commission reporting the Omaha-based company's acquisition of a massive position in HP stock.