Short term loan provider Springleaf has been given permission to buy OneMain from parent company Citigroup, provided it sells 127 of its own branches.
The new company would be left with more than 1,800 branches nationwide.
Both firms provide personal loans of under $6,000 (Â£3,940), which have a set number of scheduled payments lasting between a few months and a few years.
Springleaf announced its plan to buy OneMain for $4.25bn in March.
The deal hit a snag when US authorities claimed the tie-up could make it harder for people with poor personal financial ratings living in 11 states to access lines of credit.
The agreement reached on Friday with the Department of Justice and state regulators ends an anti-trust lawsuit.
Shares in Springleaf rose 11.95% on the news.
The second largest provider of personal instalment loans in the US is to buy its biggest competitor.