Carlyle Group in Washington D.C., one of the largest private equity firms in the U.S., will invest $200 million for a 15% to 20% stake Aliso Viejo-based UST Global—valuing the company at over $1 billion—according to multiple reports.

UST Global is an IT service firm providing outsourcing and technology services to a number of Fortune 500 companies. It has significant operations in India.

It posted sales of $800 million in 2015 according to the Business Journal’s rankings of largest private companies. It has 15,000 employees companywide.