Bill Gates sold about $940 million of shares in the Canadian National Railway Company, reducing one of the largest holdings of the investment firm managing his personal fortune of $117 billion.

"Cascade Investment" sold about 12% of its shares in the company, headquartered in Montreal, between April 27 and May 12, bringing its stake to about 9% or $6.8 billion, according to a Securities and Exchange Commission filing.

"Cascade" has reduced its ownership in the Canadian railway company since at least May 2021, when it still owned about 13% of the company. Justin Hoile, one of Cascade’s investment managers, has been serving on the board of the Canadian National Railway since last year.

The company’s shares have declined by 7.3% this year after rising steadily from their pandemic-era lows in March 2020.

"Cascade," headquartered in Kirkland, Washington, also owns $14.1 billion in Republic Services, a waste management company, along with $9.7 billion in Deere & Co. Cascade’s largest holding is believed to be $26.9 billion in Microsoft, the software company founded by the American billionaire. Gates stopped reporting Microsoft shares in 2020 after stepping down from its board.

The 66-year-old Gates, the world’s fourth richest person according to the Bloomberg Billionaires Index, recently entered a dispute with Elon Musk who accused him of damaging his environmental credibility by selling Tesla shares. In an interview on the BBC, Gates appeared to acknowledge that he had indeed sold shares in the electric car maker, saying he was only diversifying his investments.

Melinda French Gates, Gates’ ex-wife, 57, received shares in companies including Canadian National, Deere, and AutoNation from Cascade after the couple announced their divorce last year. She has since sold a large part of her holdings in the railway company, including shares worth $467 million in December.

The Bill & Melinda Gates Foundation Trust also sold $180 million worth of Canadian National shares since late April, reducing its stake to less than 2%, according to filing documents.