For the first time since BioWorld began tracking the biotech industry's public financings in 1999, five U.S. companies priced their IPOs within a 24-hour period and made their U.S. market debuts on a single day. Ironically, they picked June 21, the Northern Hemisphere's summer solstice. Whether the date was coincidental or a metaphor for long workdays ahead remains to be seen, but all five companies – Aptinyx Inc., Avrobio Inc., Kezar Life Sciences Inc., Magenta Therapeutics Inc. and Xeris Pharmaceuticals Inc. – started in the plus column. Eidos Therapeutics Inc., which priced a day earlier, began that trend when its shares (NASDAQ:EIDX) gained $6.12, or 36 percent, Wednesday to close its first trading day at $23.12.