By Sam Oliver

Published: 11:10 AM EST (08:10 AM PST)

Members of Apple's top brass sold a million shares of company stock Thursday, totaling $200 million in value and helping to send the stock price down $4.57.

According to Philip Elmer-DeWitt at Fortune Brainstorm-Tech, four Apple executives sold 850,000 shares of stock worth of fully vested stock Thursday morning, when Apple opened the day at an all-time high. Chief Operating Officer Tim Cook sold the largest amount -- 300,000 shares -- earning him a total of $68.8 million. $32 million of that was set aside for taxes.

Two weeks ago, Cook was awarded nearly $22 million in stock- and cash-based compensation. He assumed the role of interim CEO from January to June of 2009 when Apple co-founder Steve Jobs was recovering from liver transplant surgery.

Peter Oppenheimer, Apple's chief financial officer, sold 200,000 shares which cleared at $45.98 million. In addition, senior vice presidents Phil Schiller, worldwide product marketing, and Ron Johnson, retail operations, combined for 350,000 shares at $80 million.

All four executives cleared a combined $195.2 million before taxes on the stock sale. They were issued the restricted shares on Dec. 14, 2005, and the shares became fully vested on Wednesday.

Another three senior staffers -- Bertrand Serlet, Scott Forstall and Robert Mansfield -- also sold some shares to cover their tax burden. Together, the three of them were granted 250,000 restricted shares in 2005.

A strong market performance since the unveiling of the iPad in January has propelled AAPL stock to new heights. Apple temporarily surpassed the market cap of U.S. retail giant Walmart weeks ago, and the two companies have remained neck-and-neck for weeks. Based on market cap, Apple is the fourth-largest U.S. company, ahead of Berkshire Hathaway and behind only Exxon Mobil, Microsoft and Walmart.