MacKenzie Bezos is officially’s second-largest individual shareholder.

About 19.7 million shares are now registered in 49-year-old MacKenzie’s name, according to regulatory filings Wednesday detailing stock sales by her ex-husband, Jeff Bezos.

The transfer is a rare disclosure for a divorce whose financial terms have otherwise been shielded from the public. A King County judge had signed an order formalizing the separation on July 5.

Bezos sold 968,148 shares for about $1.8 billion between July 29 and July 31 as part of his stock-sale plan, the filings show.

MacKenzie’s 4% holding is worth $37 billion, enough to place her 23rd on the Bloomberg Billionaires Index, a ranking of the world’s 500 richest people. The value of her stake has fallen by $1 billion since April, when the settlement was first disclosed.

Bezos, 55, the founder and chief executive officer of the world’s largest online retailer and web-services company, retains a 12% stake worth $109 billion and remains the world’s wealthiest person.

The value of the transfer makes it the world’s most expensive divorce.

While Oracle’s Larry Ellison has been through multiple breakups, none has affected his ownership in the software maker. Likewise, Google co-founder Sergey Brin’s stake remained unchanged after he and Anne Wojcicki divorced in 2015.