DETROIT (AP) — Dow Chemical Co. has agreed to buy rival Rohm and Haas Co. for more than $15 billion in cash in a deal that Dow hopes will fuel its growth in a more lucrative wing of the chemical-making business.

"The addition of Rohm and Haas' portfolio is game-changing for Dow," Chairman and Chief Executive Andrew Liveris said Thursday in a statement announcing the deal.

The $78-per-share deal includes money from a Kuwaiti sovereign wealth fund and Warren Buffett's Berkshire Hathaway. The price represents a 74 percent premium to Philadelphia-based Rohm and Haas' closing share price of $44.83 on Wednesday. The Haas family, descendants of one of the company's founders, holds about 65 million shares, a 33 percent stake worth nearly $5.1 billion based on the purchase price.

Chief Financial Officer Geoffery Merszei said the quality and reputation of Rohm and Haas' businesses, brands, products and technologies — as well as its work force — make the premium worth paying.

"While it's hard to put a price on a company's culture and people, this premium recognizes the fact that Rohm and Haas is a highly-coveted asset," Merszei said Thursday morning in a conference call with industry analysts and investors.

Based on the per-share purchase price and the roughly 196 million shares Rohm and Haas had outstanding as of April 22, the deal is worth about $15.29 billion.

The companies said assumed debt will boost the total value of the transaction to about $18.8 billion.

The acquisition is part of an effort by Dow to move into the higher-margin specialty chemicals market, which may provide a buffer against ups and downs in basic chemical sales. Specialty chemicals are produced for more specific uses, compared with those produced as high-volume commodities for manufacturing.

Dow said the deal will make it the world's leading specialty chemicals and advanced materials company.