The initial public offering of HCA, the biggest U.S. for-profit hospital chain, is well oversubscribed and could price above the proposed range Wednesday, sources familiar with the situation said.

Although analysts warn of long-term risks related to HCA’s big debt and uncertainties surrounding U.S. health care reform, investor interest in the shares dwarfs the deal’s size, the sources said.

The IPO is likely to price at $30 to $31 per share, compared with the proposed range of $27 to $30, they said.

Investors hope hospital company profits will benefit from an improving economy. Only a handful of U.S. hospitals are publicly traded, and their shares suffered as they cared for rising numbers of uninsured patients in the economic downturn.

A newly public HCA could generate more investor interest in the sector, and the company could turn into a major acquirer, possibly becoming involved in Community Health Systems’ $3.3 billion takeover battle for Tenet Healthcare Corp .

The HCA offering, by owners including Bain Capital and KKR, would value the company at $15.5 billion. HCA and its owners plan to sell 124 million shares.

The shares are expected to begin trading on the New York Stock Exchange on Thursday under the symbol “HCA.”

Analysts warn that in clamoring for HCA’s shares, investors are overlooking big longer-term risks, including its high level of debt and the uncertainty surrounding health care reform.

HCA has more than $26 billion of debt, even after the company uses proceeds from the IPO to pay off borrowings. HCA’s debt exceeds the value of its assets by more than $12 billion.

The IPO is benefiting from the strong momentum created by a series of successful IPOs this year, analysts said.