FLINT, Mich. — With a successful initial public offering of roughly 15 million shares completed, Diplomat Pharmacy is preparing for its next phase of growth and expansion. A stock offering on the New York Stock Exchange in mid-October raised about $145 million for the specialty pharmacy company.

“It was time for us to step up and become a public company,” commented Diplomat chairman and chief executive officer Philip Hagerman.

The advantages that come with being listed as a public company, he noted, include “transparency, and the ability to have a balance sheet that allows us to possibly look at more acquisition opportunities,” as well as enabling the company to continue building infrastructure.

“This is the culmination of a lifetime’s work for me, yet it’s actually the start of a new chapter for Diplomat,” Hagerman said. “We’re going to be able to continue to grow, but now with public support.”

The IPO, which totaled 15.3 million shares, was priced at $13 per share, or slightly below the $14-to-$16 range that had been expected. Diplomat sold 11 million shares as part of the October 10 public offering, and existing shareholders sold 4.3 million shares. On the day of the offering, Hagerman was at the New York Stock Exchange to ring the day’s opening bell.

In the week following the offering, Diplomat’s shares traded in a range between $15.04 and $19.99 during a volatile trading period for the stock market.

The company’s shares trade on the Big Board under the symbol DPLO.

Diplomat, which operates nine locations spread across seven states, reported sales of $1.5 billion for 2013 and a net loss of $26.1 million. The company’s sales, boosted by an expanding market for specialty drugs, have grown at a 65% compounded annual growth rate for the past eight years.

Diplomat’s medication management services include a variety of programs in the areas of hepatitis, multiple sclerosis, oncology, immunology, HIV and specialized infusion therapy, among other serious or long-term conditions.

As the delivery model for health care evolves, it’s expected that specialty pharmacy will play an increasingly larger role. The “specialty pharmaceutical” segment is viewed as the fastest-growing segment of the industry, with annual sales volume of roughly $63 billion and 300 medications now classified as specialty drugs. It’s estimated that eight of the 10 best-selling drugs will fall in this category by 2018.

“There are a lot of changes coming in health care, and it’s going to require a nimble entrepreneurial type company that doesn’t forget about the patients,” Hagerman said. “We’ve been able to fill a need in the industry and, frankly, I think we have raised the bar in specialty pharmacy.”

Hagerman founded Diplomat in 1975. The company describes itself as the nation’s largest independent specialty pharmacy.