A $1,000 reward is being offered for information leading to the arrest of a man wanted for robbing a bank Monday in the Loop. Citibank in the 100 block of North Michigan Avenue was robbed about 9:50 a.m. Monday, according to the Federal Bureau of Investigation. In the robbery, a man believed to be 30 to 40 years old showed a note demanding money and implied he had a handgun, authorities said. Officials describe him as a 5-foot-6 to 5-foot-7 white man with a medium build wearing a black-and-white hooded sweatshirt with black pants and shoes.Authorities declined to say how much money was taken in the robbery.Anyone with information about the suspect's whereabouts can anonymously submit a tip by calling 312-421-6700 or at tips.fbi.gov. Officials described the suspect as a white man in his 30s, about 5-foot-6 with a medium build. He was wearing a black-and-white hooded sweatshirt with black pants and shoes.FBI