Air conditioned lounges at the U.S. Open. Exclusive tea parties at an art installation in Manhattan. Hard-to-get reservations at popular restaurants. These are just a few of the recent “perks” that credit card issuers like American Express and JPMorgan Chase are offering the holders of their premium cards, the Amex Platinum and Chase Sapphire Reserve, respsectively. And while both companies recently announced price hikes on their annual fees, the perk race seems to be paying off.

“The consumer base for premium cards is the fastest growing part of the cards business,” said Amanda Mull, who writes the Buying Power column for Bloomberg Businessweek. “They’re onboarding more and more people, and more and more of these cards are coming to market.”

The business model, wrote Mull in a recent story, revolves around catering to the wealthiest consumers, and for good reason. An analysis of federal data earlier this year suggested that the top 10% of income earners were responsible for nearly half of all consumer spending.

“Marketplace” host Kai Ryssdal spoke to Mull about her reporting. To listen, use the media player above.