Shake Shack is an American multinational fast casual restaurant chain based in New York City. It started out as a hot dog cart inside Madison Square Park in 2001, and its popularity steadily grew. In 2004, it received a permit to open a permanent kiosk within the park, expanding its menu from New York–style hot dogs to one with hamburgers, hot dogs, fries and its namesake milkshakes. Since its founding, it has been one of the fastest-growing food chains, eventually becoming a public company filing for an initial public offering of stock in late 2014. The offering priced on January 29, 2015; the initial price of its shares was at $21, immediately rising by 123% to $47 on their first day of trading. Shake Shack Inc. owns and operates over 400 locations globally.