A global wave of privatization by cash-strapped governments in the 1990s opened the door for financiers to purchase and manage infrastructure en masse. Macquarie pioneered a new approach when the firm realized that it could purchase the right to manage a public asset, then spin out ownership to investors, collecting fees at every stage of the process. If things went off the rails, the investors—often pension funds or individual retirees—would be the ones left holding the bag. The “Macquarie model” caught fire on Wall Street. Private investment in infrastructure rose to a record $413 billion last year, according to the data firm Prequin.