It is a team effort, he stressed, with the Philadelphia Industrial Development Corp., Select Greater Philadelphia, Greater Philadelphia Chamber of Commerce, and the state, among others, all playing a role.
About 40 of his department's 60 employees are devoted to keeping existing firms happy, Greenberger said. The work includes maintaining an early-warning system of building owners, real estate brokers, and lawyers to track companies with leases coming up or those thinking of making a move.
The remaining third of Greenberger's staff is targeted at bringing business here. That effort includes selling the city as fertile ground for growth.
"The knock against Philadelphia is we are not business-friendly," Greenberger said. "We have attacked that in 20 different ways," including streamlining regulations and revamping zoning and tax structures.
While the unemployment rate continues to run unacceptably high, the number of city residents with jobs - 596,000 - is as high as it has been since December 2001, Greenberger said.
His office's recent success stories include small but significant steps in luring high-tech start-ups, software firms, and the venture capital they need.
"It is really hard to go out and grab some firm from far away and convince them to come here without some sort of huge incentive," he said. "Cities do not have that kind of money."
While it can offer a variety of financial incentives, the city often relies on persuasion and a bit of geographic jujitsu to bring firms, particularly suburban operations, here.
Bentley Systems Inc. is a case in point.
The Exton-based software company relies heavily on young, tech-savvy employees, many of whom live in the city.
Mayor Nutter, in discussions with the company, suggested it could benefit from opening a satellite office in the city to attract local talent unwilling to trek to the outer reaches of Chester County.
Chief executive officer Greg Bentley bit and opened a satellite office at 1601 Cherry St. with 50 employees.
"He found that it worked. He got his pipeline to young people living in the city," Greenberger said. "He also found that his own employees currently living in the city want to be there. Our feeling is: Great, these things are going to morph from satellite offices to real offices."
Other firms have followed, including Brand.com, which manages the online reputations of its clients. The firm recently moved from West Chester to Washington Square with about 100 employees. It is planning to hire another 100 over the next year, Greenberger said.
"We don't need to be the initiators of all these deals," he said. "All we are trying to do is unlock a culture, to start a bit of a stampede to be part of a trend."
Josh Kopelman is part of the trend. The venture capitalist last year moved his investment firm, First Round Capital, from West Conshohocken to University City to be closer to the start-ups he might want to support.
"I have offices in San Francisco and New York. With big cities, you have bureaucracy and red tape," he said. "Philadelphia was engaged and proactive. The city was great."
It is that kind of testimonial that makes Greenberger's difficult job a little easier.
In the coming months, he said, his office expects to announce the arrival of two more companies in the city.
"This is a story of us positioning the city properly," he said. "A lot of what happens relies both on the plan and a little bit of circumstance. Luck does not happen. You put yourself in the path of luck."