Managing rapid growth is a huge challenge for young businesses. Even start-ups with glowing reviews and skyrocketing sales can fail. That’s because new ventures and corporate initiatives alike have to sustain profitability at scale, according to Harvard Business School senior lecturer Jeffrey Rayport. He has researched some of the biggest stumbling blocks to long-lasting success and explains how to make the tricky transition out of the start-up phase successfully. With professors Davide Sola and Martin Kupp of ESCP Business School, Rayport cowrote the HBR article “The Overlooked Key to a Successful Scale-Up.”