Blackstone Group and Apollo Management, the private equity groups, are in talks to buy Chemtura, a manufacturer and marketer of speciality chemicals, in what would be one of the bigger US buy-outs this year.

Chemtura said in December that it would consider whether to sell certain businesses, change its capital structure or entertain an outright sale. At the time the company, which makes chemicals used for crop protection, packaging, home pools and construction, hired Merrill Lynch to guide it through the process.