Dunkin’ Brands Group Inc., the Canton, Mass.-based operator of Dunkin’ Donuts and Baskin-Robbins ice cream stores, expects to offer 22.25 million common shares at $16 to $18 each in its initial public offering. An offering at the top of the range would be valued at about $400 million, MarketWatch reported. In an amended Form S-1 filed today with the Securities and Exchange Commission, the company said it offered the underwriters an option on 3.34 million more shares. The company distributes its products at more than 16,000 outlets in 57 countries. Its shares are to trade on the Nasdaq Stock Market under the symbol DNKN.