PRINCETON, N.J. (AP) — Rockwood Holdings Inc. said Thursday that two KKR partners have resigned from its board, which comes after the private equity firm slashed its stake in the chemicals maker.

KKR formed Rockwood in 2000 and took it public in August 2005. Just after the IPO, the firm owned about 38 million Rockwood shares. It has since been decreasing its stake, with a big sale of 6.9 million shares announced in November. According to data provider FactSet, KKR today owns fewer than 1 million shares, or a 1.2 percent stake, in Rockwood.

The resignations of Todd Fisher and Brian Carroll, both partners at Kohlberg Kravis Roberts LLC, are effective immediately. They had both served on the board since 2000.

The company did not name replacements, saying it has trimmed its board to five directors.

Rockwood, which is based in Princeton, N.J., also said Thursday that it may buy back up to $400 million in shares of its stock this year.

Reducing the amount of outstanding stock is one way companies can reward investors. Doing so can make an individual shareholder's stake more valuable and boost earnings per share.