By Katya Wachtel and Peter Rudegeair

At SAC Capital Advisors’ sprawling Stamford, Connecticut headquarters on Thursday morning,  security guards barred reporters from getting too close to the office building, holding them to an intersection a few hundred yards from the driveway.

A security guard said SAC had not added any extra security at 72 Cummings Point Rd today, when federal authorities charged Steve Cohen’s $15 billion hedge fund with wire and securities  fraud in connection with its long-running insider trading probe. But those who know the location  disagreed.

Grace DeVito, a portrait artist who lives around the corner from the Cummings Road office, said there was a “different feel” around the place today. She walked past the so-called campus with her two dogs and her daughter on Thursday morning and observed that two security guards were inspecting incoming cars to see if they had a sticker to park in the SAC parking lot. “Usually there’s no one out,” Grace said, referring to the guards.

Meanwhile, at SAC’s New York office, signs of heightened tension were more difficult to detect. On the surface at least, it was business as usual at the shiny glass office tower at 510 Madison Avenue, where SAC has several floors and its own elevator bank.

An investment banker who was at 510 Madison for a meeting said earlier in the morning he had greeted several SAC workers he knows. The man, who gave only his first initial J due to ongoing friendships with SAC employees, said the  people with whom he spoke were in good spirits, relaxed,  and it was “business as usual.”