Shoppers carrying bags walk up Fifth Avenue in New York City.

Americans are diving deeper and deeper into the red.

As of this month, outstanding consumer debt exceeded $4 trillion for the first time, according to the Federal Reserve.

Relatively strong holiday spending, particularly in November, and increasing credit card debt added more than $41 billion in outstanding balances at the end of 2018, according to LendingTree, a loan comparison website, which analyzed the data from the Fed.

In addition, a steady rise in student loan balances, as well as an increase in the cost of automobile financing in the fourth quarter, contributed another $80 billion.

At these levels, consumers are spending about 10 percent of their disposable income on nonmortgage debts, including credit cards and auto, personal and student loans, said LendingTree chief economist Tendayi Kapfidze. Ahead of the Great Recession, that averaged about 13 percent, he added.

"It's a level of debt that's pretty manageable overall," Kapfidze said. "Of course, for any one individual, you have to make sure you are not taking on more debt than you can handle."