The discovery of the new rule, as reported by The Wall Street Journal, comes one day after Apple held its annual shareholders meeting, where similar changes to corporate governance measures relating to executive stock holdings were up for vote.
According to a notice on Apple's investors webpage, the requirement took effect on Feb. 6, roughly one month after the company first issued its definitive proxy statement.
Interestingly, the policy is somewhat contrary to a similar proxy proposal that shareholders voted against on Wednesday. Apple's board urged a vote against Proposition 5, titled "Shareholder Proposal Entitled Executives to Retain Significant Stock," which recommend executives retain 33 percent of their stock holdings until retirement.
Apple's implementation of the executive stock holding policy comes amidst growing pressure from shareholders concerned over the company's decining stock price, which has slipped over 36 percent since hitting a high of just over $700 in September 2012. AAPL closed at 441.40 on Thursday after shedding $3.17, or 0.71 percent, from its price at the opening bell.