"If approved, this plan in conjunction with previous equity compensation plans, will dilute existing shareholders by a company estimated 14.2 percent," Winters wrote in one of the letters.
"The company expects that the 2014 plan will award a mix of 60 percent options, 40 percent full value shares, resulting in the issuance of 340,000,000 Coca-Cola shares," he continued. "At the current share price, these shares would be worth approximately $13 billion. In effect, the board is asking shareholders for approval to transfer approximately $13 billion from all of our pockets to the company's management over the next four years."
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However, Coke disputes this characterization.
"The 2014 Equity Plan incorporates a number of 'best practice' and shareowner-friendly provisions, such as no re-pricing of stock options, no liberal share counting and 'double-trigger' change in control vesting," Coca-Cola said in a written statement to CNBC.
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"The long-term equity compensation program is tied directly to the achievement of specific business goals and the financial health of the company," the company explained. "Therefore, if the company does not meet these goals, these awards are not earned. This pay-for-performance philosophy has been a consistent cornerstone of the program through the years and remains unchanged."
Coke added that the equity plan is not a change in the company's long-term equity compensation practices. "The plan is not limited to senior executives, but extends to a large group of employees and is important for incentive and retention," the company said. "Approximately 6,400 were eligible in 2013. The amount of long-term equity compensation awards granted each year are within industry norms."
One concern Winters expressed in his letters was that the equity plan would offset the value of Coke's ongoing share repurchase program. In the letter, Winters said he suspected that the repurchased shares would merely offset the stock issued by the equity plan.
"At a time when Coke is facing slowing growth in both sales and profit, we do not believe it is in the best interest of shareholders to compound the company's headwinds by significantly diluting shareholders," Winters wrote.