President Obama is hosting a cyber-security summit at Stanford University today, but three of the top tech companies in the United States won’t be represented there.

The White House issued an invitation to Facebook’s CEO Mark Zuckerberg, Yahoo CEO Marissa Mayer, and Google executives Larry Page and Eric Schmidt to help bring attention to Obama’s summit, but they turned the invitation down according to Bloomberg News.

The event will feature a speech from Obama and a private lunch with tech officials to highlight new initiatives demonstrating a commitment to cyber-security.

White House Deputy Press Secretary Eric Schultz told reporters aboard Air Force One that the White House was “very pleased” with the participation of the summit although some of the biggest names in the tech community turned down the invitation.

“I think if you look at who will be joining us over the next day or so, you’ll be looking at industry leaders in the tech industry, in the privacy advocacy community, in academia and government, and business leaders from across the board,” Schultz said. “So we are gratified and we welcome their participation.”

Throughout Obama’s presidency, Zuckerberg, Mayer, Page, and Schmidt have all played a role in his key fundraising and policy goals.

In the early days of Obama’s presidency, Zuckerberg lunched with President Obama and even hosted a friendly town hall for the president at the Facebook headquarters. Zuckerberg also supported President Obama’s push for immigration reform, pouring millions into FWD.us to back politicians of both parties who were committed to reform.

Yahoo!’s Mayer, then an executive at Google, donated heavily to Obama for his 2008 campaign and was even a bundler for the president in 2012.

Google’s Schmidt endorsed Obama in 2008 and even hit the campaign trail for him. He also advised Obama’s re-election campaign, offering campaign manager Jim Messina advice as he planned the digital effort. Schmidt also served on Obama’s Council of Advisors on Science and Technology announced in 2009.

The top tech community’s reluctance to meet with Obama stems from their disappointment with Obama’s response to revelations that the National Security Agency was collecting and holding mass amounts of private data on American citizens.

In March 2014, Zuckerberg and Schmidt attended a meeting at the White House of tech executives to address privacy concerns after the fallout of the NSA spying practices.

After the meeting, Zuckerberg issued a statement citing skepticism about the role of government in the future of privacy and security.

“The US government should be the champion for the internet, not a threat. They need to be much more transparent about what they’re doing, or otherwise people will believe the worst,” he wrote. “I’ve called President Obama to express my frustration over the damage the government is creating for all of our future. Unfortunately, it seems like it will take a very long time for true full reform.”