ABC Supply Co. has closed on the largest acquisition in its history, the purchase of Bradco Supply Corp., a $1.5 billion-a-year distributor of building materials.

ABC, based in Beloit, did not disclose the price it paid.

In acquiring Avenel, N.J.-based Bradco, ABC adds 129 locations, bringing its total to 479 across 44 states. The added revenue from Bradco is expected to take ABC’s annual sales beyond $4 billion.

ABC describes itself as the country’s largest wholesale roofing distributor and one of the largest distributors of siding, windows and other select exterior building products.

Bradco was founded in 1966 by Barry Segal. The company was sold to Advent International, a Boston private equity firm, in 2008. Advent said in May that it would continue to own a stake in the combined business.