Six years after acquiring the former Sunquest Information Systems for $404 million to start a new division, Misys Healthcare Systems decided it wanted back out of the business and is selling its Tucson operation for $381.5 million.

What is now known as Misys’ Diagnostic Information Systems division is being acquired by Vista Equity Partners, a San Francisco private equity firm that concentrates on investments in software and technology-enabled services. The deal is expected to be finalized in October.

In this year’s Book of Lists compiled by Inside Tucson Business, the company said it had 600 employees in Tucson. Last August, Misys consolidated its local operations into a new 120,000-square-foot building at 250 S. Williams Blvd. in Williams Centre.

For the fiscal year ended May 31,

The Diagnostic Information Systems division reported a profit of $12 million on $80 million revenue for Misys’ fiscal year ended May 31.

Under the terms of the agreement, Vista Equity Partners will enter into a multi-year agreement for other Misys divisions to resell

Diagnostic Information Systems product, which includes Misys Laboratory Information System, a highly regarded 25-year-old software system that manages specimen data from requisition entry through tracking to final cumulative report production.

Officials at Vista Equity Partners did not return requests for comment.

For Misys, the decision to sell is part of a refocusing away from its hospital-oriented businesses to ambulatory healthcare services. The company has struggled financially. Protracted buyout negotiations fell through last October.