Cardlytics saw one in five debit and credit card swipes in the United States. In 2016 its platform analyzed more than 18 billion purchases across 94 million accounts, drawn from over 2,000 banks and credit unions. The Atlanta company used that data to place cash-back offers inside online banking, where customers already checked their balances. Bank of America alone supplied about half of its users when it went public in February 2018.

Purchase Data, Put to Work

Scott Grimes and Lynne Laube co-founded Cardlytics in 2008. Their first product, Cardlytics Direct, turned a bank's website and app into an ad channel. A shopper saw an offer from a retailer, paid with a card, and got cash back. Marketers liked it because Cardlytics could show which offers led to real sales. Banks liked it because they shared in the revenue. By September 2017, Cardlytics worked with 2,041 financial institutions.

One Big Bank Partner

Cardlytics priced its IPO at $13 a share in February 2018 and listed on the Nasdaq Global Market as CDLX. The prospectus flagged its dependence on Bank of America, which supplied about 51 percent of its bank users in the first nine months of 2017. Lloyds, its largest partner in Britain, supplied about 9 percent. Cardlytics is still based in Atlanta and still trades on Nasdaq as CDLX.

Cover: The Card Player, Rembrandt van Rijn. Art Institute of Chicago, public domain. Chosen for a card player (card-linked offers).