Emdeon Inc soared in its trading debut on Wednesday while Starwood Property Trust Inc fell slightly after their respective initial public offerings.

Emdeon shares were up 11.6 percent in late morning trading on the New York Stock Exchange, at $17.29, after rising as high as $18.24. Emdeon, a health information technology provider, sold 23.7 million shares at $15.50 each to raise about $367 million in its IPO.

Starwood Property, a real estate investment vehicle that also listed on the Big Board, edged down to $19.75, or 1.3 percent less than the $20 price set for its $810 million IPO, the largest of the year so far in the United States.

Both companies increased the size of their IPOs on Tuesday prior to their pricing to meet investor demand.

Nashville, Tennessee-based Emdeon provides software that links U.S. healthcare providers such as hospitals, pharmacies and doctors with private and public insurers. Last year, it processed almost half of the electronic payment claims made in the United States.

Emdeon stands to gain from whatever reforms emerge from the Obama administration's health care reform, its chief executive said.

No one knows how that reform will shake out, but there are consistent themes, such as more and better information exchange, that are all things that will benefit our company, Emdeon Chief Executive George Lazenby told Reuters in an interview.

Emdeon had revenue of $444.4 million in the six months ended June 30, up 5 percent from the year-earlier period.

Despite that tepid growth, Emdeon likely benefited from strong investor interest in the sector that has also buoyed the stocks of chief rivals such as Eclipsys Corp and Cerner Corp , which have risen by 21.6 percent and 68.2 percent respectively this year, an analyst said.

They are dominant in their market. Investors are taking a look at this sector, so it makes sense that the leader would command a premium, said Francis Gaskins, president of advisory firm IPO Desktop.

If Emdeon held its first-day gains, it would be 15th out of 17 IPOs this year, excluding those by real estate investment trusts, to rise in initial trading.

Starwood Property, which was created in May, intends to invest the proceeds in commercial mortgage-backed securities sold under the U.S. government's public-private investment program, or PPIP.

In its prospectus, Starwood Property said there will be a significant supply of distressed investment opportunities from sellers over the next five years.

Starwood Capital Group, controlled by Barry Sternlicht, has previously formed companies such as Starwood Hotels & Resorts Worldwide and property finance company iStar Financial Inc .

(Editing by Steve Orlofsky)