Bill and Melinda Gates announced their divorce on Monday, after 27 years of marriage.

“After much thought and effort on our relationship, we have decided to end our marriage,” the couple said in a statement posted on Twitter. “We’ve raised three amazing children and established a charity that operates all over the world to help all people live safe, meaningful lives.”

Most of the world’s most valuable fortunes – presently estimated at $145.8 billion according to the Bloomberg Billionaires Index – and one of the world’s biggest philanthropic activities are at stake. The Bill and Melinda Gates Foundation has given away more than $50 billion, helping to counter Covid-19, leading the drive on climate change, and fighting for women’s rights.

Bill Gates, the co-founder of Microsoft Corporation, is the world’s fourth-richest male at the age of 65. Melinda Gates, 56, is a former Microsoft executive who has been a vocal spokesperson for public health and gender inclusion in her capacity as co-chairwoman of the Gates Foundation.

Though the divorce is certain to shake up the world’s richest people’s charts, the couple insists it would have no effect on their philanthropic behemoth.

“Bill and Melinda will continue to serve as co-chairs and trustees of the Bill & Melinda Gates Foundation,” a foundation spokeswoman said in an emailed statement. “There are no plans to alter their positions or the organization. They will continue to collaborate to develop and authorize foundation plans, lobby for the foundation’s concerns, and set the general course of the organization.”

It’s the second shocking divorce of the world’s wealthiest citizens in recent years, after Jeff Bezos and MacKenzie Scott’s breakup announcement in 2019.

The separation, which shared the couple’s interest in Inc., instantly elevated MacKenzie to the ranks of the world’s wealthiest citizens. In the months that followed, she rose to become one of the world’s most powerful philanthropists, donating billions of dollars to charities that are mostly forgotten by billionaire donors.

The Gates fortune could be more difficult to divide than the Bezos fortune, which was primarily contained in Amazon stock.

Bill Gates’ net worth started with Microsoft, but shares in the tech company now likely account for less than 20% of his fortune. He’s transferred a large portion of his stake to the Bill & Melinda Gates Foundation over the years, though his exact stake hasn’t been revealed since he left Microsoft’s board last year.

Cascade Investment, a holding company founded by Gates with the profits of Microsoft stock purchases and dividends and managed by Michael Larson, is his most valuable possession. Via Cascade, Gates has investments in real estate, oil, and hospitality, as well as stakes in scores of publicly traded firms such as Canadian National Railway and Deere & Company.

The big mystery about the couple’s base and family office, according to Monica Mazzei, a divorce attorney, and associate at Sideman & Bancroft LLP in San Francisco is how much they plan to work together in the future.