By Matt Jarzemsky 
 

Medical-services provider Envision Healthcare Holdings Inc. is set to test investor demand with what could be the biggest U.S.-listed initial public offering in three weeks, ahead of a late-summer lull for IPOs.

The company expects to sell 35 million shares for $20 to $23 each, according to a regulatory filing. The deal would raise $805 million at the top of that range, marking the largest IPO since building materials maker HD Supply Holdings Inc.'s $1.1 billion debut in late June.

Envision is coming to market just ahead of a seasonally slow season for IPOs, as money managers leave the office for summer vacation. Since 2005, only two U.S.-listed IPOs have priced during the last two weeks of August, according to Ipreo, a capital markets data and advisory firm.

Envision is returning to public ownership after a $2.9 billion buyout by private-equity firm Clayton, Dubilier & Rice LLC in February 2011. The investors also assumed $300 million in debt carried by the company-then named Emergency Medical Services Corp. Private-equity firms have been particularly active in pursuing IPOs for their portfolio companies this year, taking advantage of rising stock-market values.

Envision provides hospital staffing and ambulance services to healthcare centers and government agencies. The three months ended June 30, its profit rose 22% to $9.6 million as revenue climbed 12% to $899 million.

The company, based outside of Denver, was formed in 2005, when Canadian private-equity firm Onex Corp. combined ambulance company American Medical Response and hospital-staffing provider EmCare. Onex took the company public later that year. During CD&R's tenure, Envision has expanded into services for patients after they have been discharged from hospitals.

Elsewhere in the IPO market this week, Third Point Reinsurance Ltd., the reinsurer whose investable assets are managed by Dan Loeb's Third Point LLC, expects to see its debut raise up to $322.2 million.

Envision is slated to start trading on the New York Stock Exchange Wednesday under the symbol "EVHC." Goldman Sachs Group Inc. (GS) is leading the deal with Barclays PLC (BCS), Bank of America Corp. (BAC) and Citigroup Inc. (C).

Write to Matt Jarzemsky at matthew.jarzemsky@dowjones.com

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