The stock price of Realty Income is likely to decrease in the short term by the amount of the dividend on the ex-dividend date, as the market adjusts for the payout. This is a common occurrence and is typically priced in by investors. The importance is significant as dividends are a key component of shareholder returns, especially for a company like Realty Income that pays monthly dividends. The confidence level is high due to the predictable nature of stock price adjustments on ex-dividend dates.