Portillo's stock soared more than 40% after it opened at $26.00, or 30% above $20 IPO price.The company is known for its Chicago-style hot dogs, planned to raise $375 million with a market value of $1.3 billion. It was acquired by Berkshire Partners in 2014,which owns and operates a fast food chain with 67 restaurants in the Chicago metropolitan area. While the company saw a slight drop in footfall in the third quarter of 2021, it will open 600 chains in the U.S. in the future.