Shake Shack is starting to look cheap after a sharp selloff on beef-cost and consumer worries, despite solid growth and margins. Q2 revenue grew 17.2%, restaurant-level margins reached 23% and free cash flow is positive. It owns no real estate, so it is a bet on the brand, restaurant economics and expansion across its 703 restaurants. The key question is whether those margins hold as it grows. x.comÂ