Next week it will further reduce its stake by selling about 1 million shares at the IPO. That will leave UEF with about 2.6 million shares in SKS that won’t be part of the public float.

The shares, due to be priced July 28 to 30, are expected to value SKS at just over $1 billion, with the publicly traded shares worth an estimated $275 million.

At that price, about $16.38 a share, Unitus Equity Fund’s 3.69 million shares would be worth about $60.4 million, a significant return on its $6 million investment, made between 2006 and 2008.

How those proceeds will be distributed remains unclear. UEF, which is registered in the Cayman Islands, hasn’t disclosed who all of its shareholders are and how much they have invested. It also is unclear who among Unitus’ founders and board members invested in UEF. The fund invested in SKS through an entity called Mauritius Unitus Corp., registered in the tiny island nation of Mauritius off the coast of Africa.

In response to questions from the Business Journal, Unitus co-founder and chairman Joseph Grenny declined to provide specifics.

“We candidly do not feel this is a productive line of inquiry for Unitus,” a spokesman for the charity wrote in response to an interview request by the Business Journal. The UEF investors are considered “promoters” of SKS stock and are prohibited from making public statements that may affect the stock’s pricing during a “quiet period” around the IPO, according to a Unitus spokesman.

However, in an earlier interview, a Unitus official gave some details about the Unitus Equity Fund investors. The fund raised $23.6 million in 2007 to invest in SKS and other microfinance companies. UEF’s investors fell into four main groups, each contributing about one fourth of the fund total, according to the interview with Christopher Brookfield, who was the fund’s director at the time and a Unitus employee. The interview was published on a blog run by a Unitus board member.

He identified the investors as: “Unitus board members and friends; Omidyar Network; professional investors who are leaders in technology VC (venture capital), private equity, and health care; and a group of socially responsible investors managed by Abacus Wealth Management.”

Brookfield declined to be interviewed for this article.

Regulatory filings indicate some Unitus board members had invested in UEF. Unitus board member and co-founder Michael Murray’s charitable foundation had about $250,000 invested in the fund, according to his foundation’s 2008 tax filing, the latest available.

Former Unitus board member Geoff Woolley, who is helping lead the reorganization of Unitus following its closure this month, is a member of the Unitus Equity Fund investment committee and also sits on the SKS board of directors. Woolley holds 36,000 shares of SKS stock, according to the SKS prospectus.

The nonprofit Unitus charity also appears to be an investor in UEF. Through a subsidiary, it had $142,647 invested in UEF, according to a 2008 tax filing.

The Unitus charity channeled about $6.6 million in donor cash and services to SKS. This support, which is separate from the private investment capital, provided operational funding, technical advice, and other help that Unitus says is now no longer needed.

During the period when those donations were made, SKS grew rapidly. In 2003, when Unitus began providing SKS with assistance, the microlender had about 10,000 borrowers. Today, SKS serves more than 6 million borrowers.