John D. Muggeridge, vice president and regional general manager of Fidelity Investments, walks through a corridor of the company’s newest building in Smithfield.

The Providence Journal / Bob Thayer

SMITHFIELD — The state’s largest office building is now open for business.

Fidelity Investments, which opened a regional headquarters in Smithfield in 1998, is in the process of completing a four-story, 577,000-square-foot structure near its original headquarters off Douglas Pike, and the first of an expected 1,000 additional employees have already begun moving in, according to John D. Muggeridge, vice president and regional general manager of Fidelity.

“We will now have two Fidelity headquarters, which is pretty unique,” Muggeridge said. “The group moving in is Equity Management Group, managing stocks for institutional shareholders. It means that the portfolio managers and research analysts and an equity trading desk will be right here in Smithfield, serving institutional investors. It’s the first time an equity money management group for Fidelity has been outside of Massachusetts, so this is a big deal for us. In just this group they are actively managing assets, as of June 30, of $165 billion. That’s billion — with a B. I find that kind of cool.”

He said the new building is not quite finished.

“It’s so big that there are portions of the building that are still being worked on,” he said. “We started moving people in in mid-July. We have had two moves so far. There is just shy of 300 people working up there. Every couple of weeks from now until, I believe, the end of October we are going to be moving more people. After a couple of years of construction and all our topping-offs and ribbon-cutting, it has actually come around.”

He said the launch of the new building means that Fidelity now occupies 1.1 million square feet of office space in Smithfield.

Muggeridge said that when Fidelity in 2005 announced plans for the new building, at 900 Salem St., the prediction was that 1,000 new jobs would come to Smithfield. When the structure is completed, he said, “We will have them.”

The building will also house Pyramis Global Advisors, Fidelity’s institutional asset management unit, and Fidelity Personal Investments, the retail brokerage unit.

Dennis G. Finlay, Smithfield town manager, said that the town now receives $1.5 million in annual tax revenue from Fidelity’s operations, at 100 Salem St. With the opening of the new building that figure is expected to rise by $1.1 million, he said.

Muggeridge, noting that this year was the 10th anniversary of the opening of the first building, said, “In ten years we have gone from zero square feet to over one million, and from zero employees to 2,700.”

He said Fidelity invested more than $200 million in the new structure. “We have used a million hours of trade hours to build it,” he said. “If you combine the $200 million with what we spent on the first two buildings, our investment in Smithfield is over $300 million.”

Is Fidelity contemplating further expansion?

“You never know,” Muggeridge said. “We are always looking at our portfolio to see what we need.”

Fidelity describes itself as one of the world’s largest providers of financial services, with custodial assets of more than $2.7 trillion, including managed assets of more than $1.3 trillion. Fidelity offers investment management, retirement planning, brokerage, and human resources and benefits outsourcing services to more than 22 million individuals and institutions as well as through 5,500 financial intermediary firms.

The firm is the largest mutual-fund company in the United States, the number-one provider of workplace retirement savings plans, one of the largest mutual fund supermarkets and a leading online brokerage firm.

tmorgan@projo.com