Warren Buffett's company said Monday it plans to spend about $9 billion cash to add specialty chemical maker Lubrizol Corp. to the eclectic mix of businesses inside Berkshire Hathaway Inc.

HUM, Humana Inc.

HUM is a full-service benefits and well-being solutions company, offering a wide array of health, pharmacy and supplemental benefit plans for employer groups, government programs and individuals, as well as primary and workplace care through its medical centers and worksite medical facilities.

HUM, Humana Inc.

Over its 50-year history, Humana has consistently seized opportunities to meet changing customer needs. Today, the company is a leader in consumer engagement, providing guidance that leads to lower costs and a better health plan experience throughout its diversified customer portfolio.

Warren Buffett says Berkshire Hathaway is the "dumbest" stock he ever bought.

He calls his 1964 decision to buy the textile company a $200 billion dollar blunder, sparked by a spiteful urge to retaliate against the CEO who tried to "chisel" Buffett out of an eighth of a point on a tender deal.