On Wednesday, shares of Panera Bread Company (NASDAQ: PNRA) soared after the company agreed to be acquired by private-equity investor JAB Holdings in a deal worth $7.5 billion. Assuming the acquisition closes as expected by the end of the third quarter of 2017, Panera will become a privately held company. And in the process, retail investors looking to capitalize on the fast-casual restaurant space will have lost a promising portfolio candidate.