Six months ago, on-demand home delivery was far from mainstream — a luxury for those willing to pay for convenience, skewing towards young professionals in major cities. The Covid-19 crisis changed that, almost overnight. Now everyone is ordering everything from household staples to ice cream on-demand. Existing delivery services like DoorDash and Instacart have stepped up operations, and new entrants have appeared as well; the payments platform Toast, for example, announced its own delivery offering. But there have been growing pains: food delivery companies have struggled with margins, and even marketplace giant Amazon has had to delay Prime Day, its annual sales bonanza. This upheaval, and the windfall it has brought to certain companies, also presents a novel business challenge: delivery service marketplaces have inverted from demand-constrained to supply-constrained almost overnight. As recently as mid-March, most of those marketplaces were focused on growing market share. Read more at Harvard Business Review.