With the National Football League season in full swing, the water cooler chatter on Wall Street revolves around quarterback ratings as much as it does credit ratings.

And in a cubicle just down the hall from the office of Stephen A. Schwarzman, the billionaire chief executive of the private equity giant Blackstone Group, sits perhaps the biggest football fan in finance — or at least the biggest Green Bay Packers fan.

Aaron Nagler, a staff member in Blackstone’s public affairs office, runs CheeseheadTV.com, the most popular fan-run Web site about the Packers.

At Blackstone, Mr. Nagler spends his days fielding calls from private equity reporters and the company’s Washington lobbyists. When football season rolls around, he obsesses about all things Packers — the team’s dilemma at left tackle, for example, or a new Broadway play on Vince Lombardi, the celebrated Green Bay head coach.

“CheeseheadTV is the best fan blog out there,” said Greg Bedard, who covers the Packers for The Milwaukee Journal Sentinel. “Aaron is extremely smart, but I do worry about his sanity and seriously question whether he sleeps.”

Mr. Nagler, 37, started the site with Corey Behnke, a Green Bay native who works in New York as a video editor. They met at the North Carolina School of the Arts. Mr. Nagler was performing a monologue in front of the drama department and mentioned he was from Appleton, Wis. “Go Pack,” yelled Mr. Behnke from the back of the classroom.

After five years as a working actor, Mr. Nagler took an office job at the United Media newspaper syndicate in New York to pay the bills. It was there, in 2006, that he started a Packers blog called Aaron Nagler’s Football Report.

“I think my father and two friends read it,” Mr. Nagler said. One of those friends was Mr. Behnke, who suggested that they add a podcast. The next year, CheeseheadTV was born.

Now in its fourth season, the site has come a long way, averaging 152,000 visits and 370,000 page views a month, according to the Web analytics company Compete. Thousands of fans tune in to “Packers Transplants,” a weekly 90-minute webcast filmed in Mr. Behnke’s apartment in Manhattan. Packers players and coaches appear routinely on the show. On Tuesday, Mr. Nagler interviewed Tom Crabtree, a rookie tight end.

Mr. Nagler received credentials last year to cover the N.F.L. player draft at Radio City Music Hall, one of the few from a fan Web site to get an invitation.

Like Packers fans, the CheeseheadTV faithful are a loyal bunch. Last year, after the soundboard broke in the middle of a webcast, Mr. Nagler appealed to his readers, saying that the site needed $500 for a replacement. Within two days, he said, the money was wired in via PayPal from all over the world.

Mr. Nagler lives in Queens with his three daughters and his wife, Carolyn, who says she has come to love the Packers. “His passion is infectious,” she said.

Other than a Packers schedule tacked to his cubicle wall and a hat that he wears into the office — “it’s a baseball cap, not a cheesehead,” he says, referring to the yellow wedge-shaped headgear indigenous to Packers Nation — Mr. Nagler keeps his football fanaticism under wraps.

But his avocation has leaked out. Garrett M. Moran, a senior executive at Blackstone who runs the firm’s private equity operations, says his connection to Mr. Nagler has raised his stock in the eyes of his Packers-obsessed teenager.

“My son had only taken a passing interest in what I do,” he said. “But since I told him that my colleague ran CheeseheadTV, he now thinks Blackstone is a pretty cool place.”

Although CheeseheadTV attracts sponsors, they don’t cover the costs of running the site. So Mr. Nagler is on the lookout for backers.

Has his employer considered a stake in CheeseheadTV?

“At Blackstone, we like to invest in businesses where we have an opportunity to improve them,” Mr. Moran said. “And CheeseheadTV appears to be making all the right moves.”

– Peter Lattman