Chip design stocks rallied in premarket trading. Synopsys jumped 6.7%; Cadence Design rose 5.3%; Ansys gained 2%.

The U.S. has lifted some curbs on exports of chip-design software to China, according to three companies that say they are working to restore access to recently restricted products.

Three of the world's top chip-design software developers, California-based Synopsys and Cadence Design, and Germany's Siemens, said they had been told by the U.S. Department of Commerce's Bureau of Industry and Security that recent restrictions on China-bound exports had been lifted.

" Cadence can confirm that BIS has rescinded the export restrictions set forth in the letter issued by BIS on May 23," it said in an emailed statement. "We are in the process of restoring access to our software and technology to affected customers in compliance with U.S. export laws."

Synopsys said the Bureau of Industry and Security of the US Department of Commerce informed the company that export restrictions related to China have been "rescinded," effective immediately. The company is working to restore access to the recently restricted products in China, it said late Wednesday.