WILSONVILLE, OR -- Carl Icahn has upped his stake in Mentor Graphics for the third time in a month.

According to Securities and Exchange Commission filings, Icahn now owns 10.84% of the EDA software company.

Icahn has been buying shares of the company for several months, and in the past 30 days has boosted his stake from 8%. The notorious corporate raider has met with Mentor management, although specific details are not available.

Mentor in June adopted a so-called poison pill defense that goes into effect when an investor or institution acquires 15% of its common stock. The provision allows shareholders an option to purchase a discounted share for every security they own.