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 25-year-old was on the periphery of Newcastle's 2011 Championship-winning squad, and sees comparisons with the promotion-chasing Devon side.
"When teams beat us they celebrate like they've won the league, which is a bit similar," he told BBC Sport.
"It's the same - people up their game against us, which you've got to deal with when you're a big club like us."
On Saturday, Donaldson will make his first return to his last club Cambridge, for whom he scored the goal which won them promotion back into the Football League in 2014.
Argyle are second in the fourth tier, but were beaten by Yeovil on Tuesday, only their seventh league defeat in 27 games.
"Yeovil the other night, you should've heard them when they won, " Donaldson added.
"It's not annoying, it just feels better when you beat them because we should beat teams like that, but sometimes it happens and you've just got to move on and get on with it.
"We've got so many good players here - I've not played in a squad this good since I made the step up into men's football, so I think we all push each other on."
The second largest provider of personal instalment loans in the US is to buy its biggest competitor.
[NEXT_CONCEPT]
Plymouth Argyle midfielder Ryan Donaldson says League Two teams see the Pilgrims as a major scalp.