The announcement of a $4.26 per share dividend by Equinix is significant for investors, especially considering the stock is expected to open lower by the same amount on the ex-dividend date. This decrease in stock price is a direct consequence of the dividend payout, reflecting the transfer of value from the company to the shareholders. Investors need to own the stock by the end of Monday to be eligible for the dividend, making this information crucial for short-term trading strategies.