In his February letter to shareholders, Warren Buffett wrote that Berkshire Hathaway is seeing a “gradual shift from a company obtaining most of its gains from investment activities to one that grows in value by owning businesses.” This according to a Wall Street Journal article from earlier this month. The trend is being underscored by the company’s recent bid to purchase the bankrupt power-transmission company Energy Future Holdings Corp. (including utility company Oncor) for $9 billion.

The shift began in 1999, the article says, with Berkshire’s first utility purchase, and gained steam with the conglomerate’s acquisition of Burlington Northern Santa Fe railroad in 2009. “Regulated businesses,” says WSJ, “can yield steady returns, while stock investments are more volatile but can produce bigger wins. Berkshire also operates less regulated businesses including retailers and manufacturers.”

The utility investments, the article says, “mark a different strategy than how Mr. Buffett built his firm decades ago, when he sought to buy companies like See’s Candies that required little capital investment.”