Nadella sold almost 840,000 shares of Microsoft before Thanksgiving, according to SEC filings. He still owns more than 830,000 shares, which are worth around $280 million. 

The timing of the sale has some financial analysts suspecting that Nadella is hoping to minimize his tax liability under Washington State’s new 7% capital gains law, which will take effect on Jan. 1, 2022. The tax targets individuals with long-term capital assets whose gains exceed $250,000 annually. 

“Whether that was a motivator or not, I can’t speak to that,” Ben Silverman, director of research at investment research company Verity, told the Seattle Times. “[I]t’s worth pointing out that the timing, coming about six weeks before the implementation of that [tax], is curious for a sale of this size.” 

“Satya sold approximately 840,000 shares of his holdings of Microsoft stock for personal financial planning and diversification reasons,” Microsoft wrote in a statement to Fortune. “He is committed to the continued success of the company, and his holdings significantly exceed the holding requirements set by the Microsoft board of directors.” 

Nadella sold his shares when Microsoft’s share price was just shy of reaching its all-time high of $349.67 on Nov. 22. The company has been reporting strong sales and earnings since Nadella took over as CEO in 2014 and is worth over $2.5 trillion. Since the news of Nadella’s sale broke on Nov. 30, the stock has wavered little in price.

Nadella previously sold $36 million in Microsoft stock in 2018, and around $8.3 million in 2016.

This story has been updated with a statement from Microsoft