Frontier Group Holdings, parent of Frontier Airlines, has priced its shares for its initial public offering at $19. The offering, which on Thursday began trading on the Nasdaq Global Select Market under the symbol ULCC, consists of 30 million shares, including 15 million shares offered by Frontier and 15 million sold by the carrier’s existing stockholders. Frontier expects to net $266 million for the offering, which is expected to close April 6, as it will not receive any proceeds from the shares sold by existing shareholders.