May 16 (Reuters) - Berkshire Hathaway Inc on Monday said it added new investments in Citigroup Inc and several other companies in the first quarter, as Warren Buffett’s company deployed tens of billions of dollars that had been sitting in cash. In a regulatory filing describing its U.S.-listed equity investments as of March 31, Berkshire reported new stakes in chemicals company Celanese Corp, insurance holding company Markel Corp and drug distributor McKesson Corp . Berkshire also said it sold nearly all of an $8.3 billion stake in Verizon Communications Inc. Berkshire spent $51.1 billion on equities in the quarter, including previously disclosed stakes in Chevron Corp and Occidental Petroleum Corp, computer and printer maker HP Inc and Activision Blizzard Inc, the latter an arbitrage bet. (Reporting by Jonathan Stempel in New York Editing by Chris Reese)