Retail pharmacy giant Walgreen ( WAG) weighs in as the largest pharmacy chain in the U.S., a title that's been less than impressive in the last few years. Pharmacy retailers have seen their market share squeezed by added healthcare regulations as well as increased competition from big-box stores and mail-order operations. But a shifting business could ultimately turn the tide for Walgreen and its peers. Walgreen has been expanding the scope of its stores in recent years, adding in-store medical clinics to its repertoire of products and services. Walgreen isn't alone in that new offering, but it may be best suited to execute it successfully. The chain's 7,700 stores sport a geographic footprint that big-box competitors simply can't match. Last week, the company declared a 28.6% dividend increase that brings its quarterly payout to 22.5 cents per share. That gives Walgreen a competitive 2.27% dividend yield at current price levels. Walgreen is one of the 2011 Dividend Aristocrats, having raised its dividend for at least 25 consecutive years.