The functionality, first made available to credit cardmembers last year, provides peace of mind, helping ensure that no unauthorized transactions are made while a debit card or credit card is misplaced. When locked, new transactions are blocked while previously approved recurring payments continue without disruption. Customers can easily unlock their accounts just as quickly whenever they want.

"Citi is constantly looking for ways to make banking more convenient by connecting with our customers when and how they want to be served, especially with respect to security and protection," said Elyse Lesley, Head of Digital, Client Experience, Marketing & Analytics, U.S. Retail Bank and Mortgage. "Since our customers are increasingly active on mobile or online, we're giving them another tool to directly control their account activity across the bank."

Since Citi Quick Lock became available to debit card customers last month, Citibank customers have used it to lock/unlock their debit cards at an average rate of 900 requests per day. Credit cardmembers have completed more than 1.6 million locks and unlocks since last year. According to recent Citi research, adoption of mobile banking is on the rise, with consumers using mobile banking an average of seven days per month. That rate climbs to 10 days per month for millennials. The extension of Citi Quick Lock to debit cards complements a suite of new mobile app features, including:

ATM/Debit Card PIN reset and activation of new or replacement cards
Mobile Check Deposit with increased limits and user experience enhancements
Personalized contact information for Citigold Relationship Managers and Citi Personal Wealth Management Advisors, including the ability to request an appointment from the mobile app

Citi reported this month that in the third quarter, the number of active digital customers in the North American Consumer Bank rose 13 percent year over year, while the number of active mobile users climbed 22 percent during the same period.