(Reuters) - Bain Capital is picking up a minority stake worth $250 million in business services firm Sikich, which is planning to deploy the investment to finance its expansion plans, the companies said on Thursday.

The private equity firm is the first outside investor at Chicago-based Sikich, which was founded in 1982. The $250 million is structured as preferred equity, the firms told Reuters.

Sikich Chief Executive Christopher Geier said the company had reached an "inflection point" in its growth, and Bain's involvement in the business would help Sikich take the next steps in its development.

The company has doubled in size in the last five years, according to a joint statement, and plans to further expand through new acquisitions and strategic partnerships. Bain did not disclose what Sikich will be valued at following the investment.

Sikich currently has more than 2,000 employees and operates across the U.S. and internationally. Its services include auditing, managing employee programs and succession planning.

"Sikich's differentiated business model has enabled the company to gain share in a fragmented market," said Cristian Jitianu, partner at Bain Capital Special Situations.

While large leveraged buyout volumes have dropped off in the last two years as a spike in financing costs made debt financing harder to access, the volume of so-called growth equity investments by private equity firms has remained at healthy levels, according to an April report from data provider PitchBook.