President Barack Obama on Friday will sign an executive order that aims to make it easier for the government to share classified cyberthreat information with companies, an effort designed to spur collaboration and deter hackers, the White House said.

The executive order, to be announced at a cybersecurity summit at Stanford University, reflects both the urgency White House officials are giving to cybersecurity as well as the limits to their current effort. In one reflection of that, much of the order will remain voluntary for firms, many of which are wary of government involvement in how they protect themselves from computer attacks.

One significant part of the executive order would allow the Department of Homeland Security to approve classified information sharing arrangements. DHS previously wasn't among the federal agencies that had this power. The change could be substantial, as DHS is supposed to serve as the primary interface between the government and companies when it comes to sharing information about cyberthreats.

Still, much could depend on whether intelligence agencies such as the National Security Agency and the Central Intelligence Agency participate in any arrangement that allows classified information to be shared with companies.

A significant part of the executive order is meant to push companies to share more information about cyberthreats with their peers, with the belief that if they alert each other to a new virus or malware, they can help prevent other companies from being hacked.

But participation in the “information sharing and analysis organizations” that Mr. Obama is trying to promote will remain voluntary, the White House said, which means companies can choose whether or not to become involved.