On December 20, 2023, David Nierenberg (Trades, Portfolio), through Nierenberg Investment Management Company, made a significant addition to the firm's holdings in Potbelly Corp (NASDAQ:PBPB). The transaction involved the acquisition of 216,005 shares at a trade price of $10.43, increasing the total share count to 2,925,865. Notably, Nierenberg's stake in Potbelly Corp now represents 9.60% of the company's shares.