Shares of the dividend-paying pharmacy chain have been offering a double-digit yield percentage.If you've been sifting the markets for high-yield dividend stocks to buy, you've probably noticed Walgreens Boots Alliance (WBA) offers the highest yield among stocks in the S&P 500 index.The company behind leading pharmacy chains in the U.S. and Europe lowered its quarterly dividend payout to $0.25 this year, but its stock price has been trading below$10 per share. As a result, investors who buy at recent price ...