The Federal Trade Commission said Wednesday it has ordered Delta Air Lines, Walmart and other companies to explain how they use people's personal data to set prices, AP and Fox Business report. Fox Business says the orders went to nine companies: Delta Air Lines, United Airlines, JetBlue, Lyft, Uber, DoorDash, Instacart, Target and Walmart.

The agency wants to know whether prices for plane tickets, rides, food delivery and other services change from one person to the next, AP reports. It is looking at things like loyalty programs and personal data. The FTC is also checking whether ride and delivery apps set drivers' pay using data such as their phone use.

FTC Chairman Andrew Ferguson said the agency will look hard at how the companies decide what people pay. "Consumers deserve to know whether companies use their web surfing habits or other personal data to estimate the highest price they can charge each consumer," he added, Fox Business reports.

Each company has 45 days after it gets the order to respond, Fox Business reports. The FTC said it could go to federal court to force companies to comply.

Several companies denied using personal data this way. Delta said it has "zero tolerance for discriminatory or predatory pricing," AP reports. JetBlue said fares are based on demand and seat availability. Instacart said, "We do not use personal information to set prices, and we never will," Fox Business reports. Walmart and Target have said they do not use shoppers' personal data to set or raise prices, AP reports.

Lawmakers in at least 30 states have looked at bills on pricing this year, AP reports. The figure comes from the National Conference of State Legislatures.

What we know: The FTC has ordered Walmart, Delta and other companies to share how they use personal data in pricing and pay.
What we don't: What the companies will turn over, or whether the FTC will take action.