Aurora-based Old Second Bancorp Inc., which lost $60 million last year, has disclosed that it’s operating under an agreement with U.S. regulators to increase its capital to levels higher than what’s usually considered “well capitalized.”

The publicly traded lender, which has assets of $2.5 billion, outlined its capital-raising plans in a filing last week.“Like a large number of financial institutions across the United States, we have been impacted by the general adverse economic conditions that have affected the nation and our markets over the past several years,” the bank said.  “As a result of this economic downturn and the depressed real estate markets, we have experienced a decline in the performance of our loans, particularly real estate construction and development loans.”

In late 2009, Old Second National Bank entered into a memorandum of understanding with the Office of the Comptroller of the Currency, in which it agreed to institute a variety of programs to reduce credit risk in the bank.

“We also agreed with the OCC to maintain the bank’s regulatory capital ratios at levels in excess of the general minimums required to be considered ‘well capitalized’ under OCC regulations,” the company said.

Old Second, which is participating in the U.S. Treasury’s Troubled Asset Relief Program, has about 30 branches in the Chicago area.

Its stock is trading at $2.58 a share, at the low end of a 52-week range of $2.57 to $7.47

Read the  SEC document containing the order.