Cadence Design Systems, one of the largest makers of the software used to design computer chips, is in talks with at least two buyout firms about a possible sale of the company, two people close to the matter said yesterday.

The company has held talks with Kohlberg Kravis Roberts and the Blackstone Group, and other suitors may emerge, those people said. But they warned that a deal may not happen because of the complicated risks in the company's business. Other private equity firms took a look at Cadence but passed.

Representatives for Blackstone, Kohlberg Kravis and Cadence declined to comment.