Hospital giant HCA Inc.-- co-parent of HealthONE, the largest health care system in metro Denver -- on Sunday filed its much-anticipated initial public offering, reported first-quarter earnings of $388 million and announced a $500 million distribution to stockholders.

Nashville-based HCA, which operates 162 hospitals and 106 freestanding surgery centers across the country and in England, expects to raise $4 billion with an IPO, though underwriters could bump that figure up to $4.6 billion.

About $2.5 billion will come in the form of newly issued shares, with the rest coming from current shareholders who will sell on the public market.

HCA spokesman Ed Fishbough declined to comment.

In Colorado, HCA co-owns Denver-based HealthONE with the nonprofit Colorado Health Foundation.

HealthONE hospitals include the Medical Center of Aurora, North Suburban Medical Center, St. Luke's Medical, Rocky Mountain Hospital for Children, Rose, Swedish Medical Center and Sky Ridge Medical.

Analysts and other industry-watchers have been expecting HCA to make a return to the public market for some time, especially since the passage of health care reform legislation in March.

Sheryl Skolnick of CRT Capital Group said all eyes will be on HCA as a “bellwether” of the equity markets’ appetite for health care investment. How the market receives HCA could prompt others to follow suit, she said.

“There are quite a few other companies that are going to be watching this very closely,” Skolnick said.

The HCA IPO is the largest private-equity backed offering since the financial crisis began three years ago, according to Thomson Reuters data. It’s the third largest deal announced so far this year worldwide, and the largest in the U.S. — three times larger than the next biggest U.S. deal, according to Bloomberg.

Last month, Tampa, Fla. -based investment firm Validus Group announced it would go public in a $1.5 million offering.

HCA is stepping out on solid footing. In the first quarter, the company’s revenue rose 1.5 percent to $7.54 billion while net income climbed 7.8 percent. As of March 31, HCA had about $25.9 billion of debt, or about 4.9 times its earnings before interest, taxes, depreciation and amortization.

“As a public company, we expect to have improved access to capital markets that we will be able to use to both reduce outstanding debt and reinvest into the growth of the company,” CEO Richard Bracken said in a conference call with investors.

This will mark the third time that HCA has gone public since its founding in the mid-1960s. The company has been private since 2006 when a private investor group that included affiliates of Bain Capital, Kohlberg Kravis Roberts & Co. and Merrill Lynch Global Private Equity joined HCA founder Thomas Frist Jr. in a $33 billion leveraged buyout.

With the filing, HCA now enters a quiet period until the U.S. Securities and Exchange Commision reviews its registration statement, a process that could take up to three months. Once the SEC signs off, HCA executives will go on the road making presentations to potential institutional investors and a stock price will be assigned.