Amazon.com (NASDAQ: AMZN) shares hit a record high on Monday, prompting founder Jeff Bezos to sell nearly $350 million worth of stock, marking his first disposal of the company's shares this year.

This transaction was disclosed in a Form 4 filing released after the market closed on Wednesday. The billionaire had outlined plans in a separate filing two days earlier to sell up to 15 million shares of Amazon.com, valued at over $4 billion. The recent sale represents only a small fraction of that planned divestiture.

According to the Bloomberg Billionaires Index, Bezos's fortune has swelled by $38.7 billion to $292 billion this year, driven by an 18% rise in Amazon.com shares. The company recently became the fifth publicly traded firm to reach a $3 trillion market capitalization, following a strong report on its cloud computing revenue last week.

Even after this sale, Bezos remains the largest shareholder of Amazon.com by a significant margin, owning an 8.16% stake.

The 62-year-old Bezos has accelerated his stock sales in recent years. Since 2020 alone, he has sold over $38 billion in Amazon.com shares. In contrast, from the company's initial public offering in 1997 until 2020, his cumulative stock sales totaled less than $10 billion.