Public backlash over the decision to downgrade U.S. credit has finally reached Standard & Poor's doorstep -- or at least their airspace.

An airplane was seen flying over the credit ratings agency's Wall Street headquarters Tuesday that said, "Thanks for the downgrade, you should all be fired." (Business Insider has a photo.)

Fortune revealed that the woman responsible for the stunt is a Midwestern investment banker who is fed up with politicians and the financial industry. She wished to remain anonymous because she fears for her job.

"I originally wanted to fly it over Washington, D.C., but learned that you can't do that," she told Fortune's Dan Primack.

"So I chose Wall Street instead, but didn't specifically intend it to fly over S&P. I'm just a mother from St. Louis who feels the only reason we got downgraded was people in politics."

Matthew Applegate was reportedly the pilot who flew the mission. While he was not available to comment, a competitor said that the typical charge was about $1,500.