American Express Co. agreed to buy the expense-management software company Center to augment the services it offers small businesses.

Center helps companies better manage their finances by showing in real-time how much employees are spending, and making it easier for workers to submit expense reports, according to a statement Thursday. Terms of the acquisition weren’t disclosed.

“They watch their expenses very carefully, and visibility is the key thing they need to get that done,” Eva Reda, Amex’s executive vice president for global commercial services products, said in an interview.

In addition to its well-known consumer credit cards that cater to wealthy spenders, Amex also competes in the highly competitive corporate credit-card market — working with 3.9 million small businesses in the US. The management services Center offers will be particularly helpful for those clients, Reda said.

The deal is expected to be completed in the second quarter, according to the statement.

— By Paige Smith (Bloomberg News)