ProPublica is a nonprofit newsroom that investigates abuses of power. Sign up to receive our biggest stories as soon as they’re published. On a summer day last year, a group of real estate tech executives gathered at a conference hall in Nashville to boast about one of their company’s signature products: software that uses a mysterious algorithm to help landlords push the highest possible rents on tenants. “Never before have we seen these numbers,” said Jay Parsons, a vice president of RealPage,...