Mars Inc. has agreed to purchase Wm. Wrigley Jr. Co. for $23 billion, with financing from Warren Buffett’s Berkshire Hathaway Inc., to combine the world’s biggest maker of chewing gum with the producer of M&Ms candy, Bloomberg reported.

Mars will pay $80 a share in cash for the maker of Doublemint gum, the companies said in a statement today on PR Newswire. That is 28 percent more than Wrigley’s closing share price on April 25, when it last traded.

Uniting Mars, which also makes Snickers, and the 117-year- old Wrigley creates a company to compete with chocolate maker Hershey Co. and Cadbury Schweppes Plc. U.S. confectionary companies are exploring combinations as competition intensifies and milk and sugar prices rise. Gum has higher margins than chocolate and is growing faster, Mirabaud Securities analyst Julian Lakin said.

Sales at Wrigley may rise 9 percent this year, the slowest pace since 2000, according to the average estimate of nine analysts surveyed by Bloomberg. Competition from London-based Cadbury’s Trident and Dentyne gums in the U.S. has eroded its market share.

Since November 2006, Mars has been winning market share in the U.S., while Hershey’s has dropped, a Sanford C. Bernstein analyst wrote in an April 11 note to investors.