After complaining for years that high valuations were thwarting his stock-buying efforts, Warren Buffett’s Berkshire Hathaway Inc. is back hoovering up other companies’ shares.

The conglomerate made roughly $41 billion of net purchases in the first quarter, including a boost to its Chevron Corp. stake that vaulted the investment into Berkshire’s top four common stock holdings. Buffett also disclosed that the company now holds an expanded 9.5% stake in Activision Blizzard Inc. stock -- an arbitrage bet on the video-game maker in the midst of being acquired by Microsoft Corp.

Berkshire hasn’t been this significant of a net buyer of common stocks in any quarter in data going back to 2008.