Shake Shack (NYSE: SHAK) is an American fast casual restaurant chain based in New York City. It started out as a food cart inside Madison Square Park in 2004, and its popularity steadily grew. It eventually moved to a stand within the park, expanding its menu from New York-style hotdogs to one with hamburgers, hotdogs, fries and its namesake milkshakes. The company says it uses all-natural 100% Angus beef only and says that its meat has no hormones nor antibiotics.

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 operates 136 locations internationally as of October 2017, typically located in stand-alone restaurants and shopping malls. Shake Shack also operates in stadiums, including Citi Field in New York City, Minute Maid Park in Houston, and the T-Mobile Arena in Las Vegas. It also operates 3 airport locations in New York, Los Angeles, and Dubai. There is also an outlet at the Saratoga Race Course in Saratoga Springs, NY.

In 2000, New York City began the rebuilding of Madison Square Park, which had fallen into a state of disrepair and misuse. As part of the redevelopment, restaurateur Danny Meyer helped spearhead the creation of the Madison Square Park Conservancy to help redevelop it. One of the first things the Conservancy did in its goal to improve the park was to host an art exhibit called "I <3 Taxi" inside of the park to raise awareness of the renewal effort. Meyer's Director of operations, Randy Garutti, established a hot dog cart which was run out of the kitchen of Eleven Madison, one of Meyer's Union Square Hospitality Group (USHG) operations. Over time the cart became extremely successful, and remained in operation for nearly three years.

In 2004, the city began taking bids to operate a new kiosk-style restaurant within the park; Meyer outlined his idea for the space, and opened the first Shake Shack in July 2004. From its beginning the restaurant was not designed to be a chain; it was intended to be a single shop location designed specifically for New York City. However, as the original location's sales continued to grow, the group realized that there was a market for expansion.

Since its opening, Shake Shack has grown to be the largest part of the USHG's portfolio. Its average store revenue of US$4 million is more than twice that of McDonald's average store revenue within the United States. Its popularity is such that in the summer at its original location, the wait in line for service can stretch to over an hour, especially on weekends when the weather is pleasant. A webcam on the restaurant's web page shows the current line in real time.

In June 2010, Shake Shack opened its first restaurant outside of New York City at the Lincoln Road Mall in Miami Beach's South Beach neighborhood. In April 2017 the location completed a month-long renovation that added 586 square feet of space, bringing its seating capacity to 106.

On July 12, 2010, Shake Shack restaurants were opened in the Theater District and the Upper East Side. The Upper East Side location's opening was significant because it "lifted" East 86th Street, an urban shopping district which had fallen on hard times; the location had been vacant, and even when occupied it was described by a neighbor as "never anything good there...dingy and dilapidated...almost an eyesore."

In July 2011 it was announced that Shake Shack had reached a deal with the MTA to open a location in the lower level of Grand Central Terminal. This project was delayed because the tenant occupying the space Shake Shack was to take over, Mexican eatery Zócalo, refused to vacate after the expiration of their lease and filed suit, arguing that the "bidding process (for retail space in Grand Central) is corrupted." The suit was dismissed and Zócalo appealed. In October 2012 Zócalo filed for Chapter 11 bankruptcy protection. In early May 2013, Zócalo vacated the space, and the new outlet opened for business on October 5, 2013.

Shake Shack opened its first airport location in May 2013 in JFK's newly expanded Terminal 4.

By August 2014, Shake Shack outlets had begun operating in California, Connecticut, Delaware, Washington, DC, Florida, Georgia, Chicago, Maryland, Massachusetts, New Jersey, Nevada, Pennsylvania and Texas. That month, reports surfaced that the company was preparing to go public with an IPO and was discussing an underwriting with a number of investment banks, including J.P. Morgan, Morgan Stanley and Goldman Sachs.

On January 29, 2015, Shake Shack priced its IPO at $21 per share. On the morning of January 30, 2015, it began trading on the NYSE at $47 per share under the ticker symbol SHAK. In April 2015, shares hit prices of $72, and hit a high of about $90 in May 2015. In its IPO filing, the company stated that it planned to expand its domestic footprint to 450 company-operated stores. While no end date was given for that expansion, the company indicated its intention to open at least 10 restaurants each fiscal year, though it later amended that target to 12 a year and then again later in 2016 to 14 stores a year, a goal that would result in a total of 450 stores in approximately 25 years. Later that May, Shake Shack filed for a trademark for the term "chicken shack" leading to speculation that the company would serve chicken sandwiches. The company temporarily introduced chicken sandwiches to its Brooklyn on July 7, 2015. In January 2016, Shake Shack introduced chicken sandwiches across locations in the United States, having previously started serving them at all Brooklyn Shake Shack locations.

On August 31, 2016, Shake Shack announced it would begin room service at the Chicago Athletic Association Hotel, the first hotel in America to offer in-room Shake Shack.

In November 2016 the first Houston, Texas, location opened inside the Galleria; by March 2017 another opened inside Minute Maid Park in Downtown Houston. By mid-December Delaware opened its very first in New Castle. In February 2017, the first Michigan location was opened in downtown Detroit. A second Michigan location in Troy opened on October 25, 2017. On May 10, 2017, Shake Shack opened their first Kentucky location, located at The Summit at Fritz Farm in Lexington. That June, the company announced a location would open in Charlotte, North Carolina, in late 2017, becoming the first Shake Shack in the Carolinas. California's 5 locations were all in L.A. County, until the 6th had opened in San Diego in 20 October 2017 at Westfield UTC. A second San Diego location is expected to open in Mission Valley in late 2017, along with a South Bay location in El Segundo in October.

Shake Shack has outlets in a number of international cities including Seoul, Tokyo, London, Cardiff, Istanbul, Moscow, Muscat, Beirut, Dubai, Abu Dhabi, Doha, Kuwait City, Riyadh, Manama, Tehran and Jeddah.

There are currently 136 Shake Shacks throughout the world.

Shake Shack's eponymous products are its milk shakes, which have been reviewed as some of the best in the industry. In each new location the beverage menu is customized to the local flavors of the city in which it operates.

New York Times reviewer Pete Wilson stated in his 2012 review of the establishment that the burgers were sometimes insufficiently salted and cooked to an unappealing gray.

The company has collaborated with Staple Design to create Shake Shack T-shirts, sunglasses, and other accessories , called Shake Swag.