Apple’s new high-yield savings account has netted $990 million in deposits in its first four days, Forbes reports. On its first day alone, it garnered $400 million.

Apple’s generous 4.15% annual return, the popularity of iPhones—and the meager half a percent that the average bank is paying on savings accounts—is likely for Apple’s success.

Apple savings account partner Goldman Sachs is paying just 3.90% on its consumer savings account, Marcus.

“Banks have quickly responded to the Fed’s interest rate hikes with higher mortgage and car loan rates—but savers have seen little to no increase in traditional bank deposits or savings accounts,” says Richard Crone, CEO of Crone Consulting. “There’s an outflow to CDs, money market funds and fintechs like Apple.”

Following the collapse of Silicon Valley Bank and Signature Bank and the seizure of First Republic Bank, big U.S. financial institutions have been fiercely competing to attract and retain bank customers.

Apple’s new savings account is available to holders of its credit card, the Apple Card, and can be opened in less than one minute from its iPhone. Apple Card rewards are automatically directed into the savings account.

Apple says it has 2 billion iPhone customers.

Apple and Goldman declined to comment to Forbes on their savings program.