Tim Cook cashed in $121 million in Apple stock grants on Tuesday.

He's collected over $650 million in Apple stock since he took over as CEO in 2011.

Among tech executives, only Facebook CEO Mark Zuckerberg has been paid more over that time period.

Apple CEO Tim Cook recently cashed in $121 million in stock grants, with the majority of those proceedings going towards taxes, according to an SEC filing on Tuesday.

It's part of a huge stock award dating back to 2011, when he took over as CEO. The stock is in addition to Cook's salary, which was just over $3 million in 2017.

Every year, if Apple outperforms two-thirds of the S&P 500 index, Cook receives a huge slug of previously restricted shares of Apple, which he can then sell or hold. (Apple's total shareholder return ranked 50th out of the 423 companes in the S&P 500 over the past three years, according to the Financial Times.)

These large slugs of stock make Cook one of the most highly-paid executives in the tech industry.

"Cook has been one of the highest paid CEOs in the tech industry over the past seven years, and Apple’s stock price has nearly quadrupled since he was granted 7 million shares when he first became CEO," Alex Knowlton, senior research analyst at Equilar, an executive compensation research firm, said in an email.

In total, Cook has collected more $650,382,235 in stock awards since he became CEO. After adding salary, and other bits of compensation, he's collected $701 million in pay since 2011, according to Equilar's analysis. Even after Tuesday's sales, he still holds over 800,000 shares of Apple, worth over $195,000,000 on Wednesday's opening price of $220.15.

Apple stock forms the bulk of Cook's net worth. But he also has income from his job on Nike's board of directors, and could also make money from other investments. Still, Equilar estimated last fall that a low estimate for his net worth would be around $625 million, based on Apple's stock price at the time.

"The only other CEO who has realized more value in the same time period is Mark Zuckerberg, who exercised 1.2 million options over two years," Knowleton continued. The Facebook CEO's options had a strike price of $0.06, making his options over the same time worth almost $5.8 billion.

Other tech executives are quickly catching up. Tesla CEO Elon Musk and Snap CEO Evan Spiegel both have received massive stock grants recently. Musk's was valued on paper at as much as $2.6 billion. Speigel's received $638 million as an award for taking his company public. Google CEO Sundar Pichai has collected over $404 million in stock since he took over in 2015, according to Equilar data.

Other tech executives, particularly founders, aren't compensated with equity — they already hold enough from when they founded the company.

"[Amazon CEO] Jeffrey Bezos, [Google cofounders] Lawrence Page, and Sergey Brin have not been compensated with equity over the years, with Page and Brin both taking $1 salaries," Knowlton said.

Cook plans to give the majority of his fortune to charity. Earlier this month, he transferred $5 million in Apple stock to a charity an Apple representative declined to name at the time.

Apple became the first American company with a $1 trillion market cap earlier this month.