Private-equity firm The Carlyle Group ofWashington, D.C., is selling about one fourth of its shares in Windsor-based SS&C Technologies Holdings Inc.

In a public offering announced Tuesday, investment funds affiliated with Carlyle are offering 7 million shares of common stock. Before the sale, Carlyle had 28.5 million shares, or 36.5 percent, of common stock in SS&C, the company that makes software for financial services companies and also sells software-enabled services.

After the sale, Carlyle will own 21.5 million shares, or 27.4 percent, of the common stock. The offer is expected to close July 23. Citigroup is acting as sole underwriter for the offering.

SSNC said it will not receive any proceeds from the sale. Shares of the company closed at $25.95 on the Nasdaq exchange Tuesday before the late-day announcement, but were down 7 percent in after-hours trading before Wednesday's opening bell.

The next largest shareholder of common stock is company founder William Stone, who has 14.2 million shares, or 18.2 percent.

Carlyle previously took SS&C private, then spun it back to partial public share ownership in early 2010. Stone has remained a significant shareholder at all times.

Matthew Sturdevant