The US Federal Reserve announced new rounds of stress-tests for big American banks on Tuesday, part of efforts to end the excessive risk-taking that led Wall Street to near-collapse in 2008. A first round will be conducted in the coming months under the control of the central bank, followed by a second round by the banks themselves using scenarios set by the Fed, it said in a statement. Tests will eventually be done on all banks with more than $50 billion in assets but this year they will apply only to the 19 largest banks that the Fed tested in 2011. Other banks in this $50 billion-plus category will be submitted to the tests beginning in September 2013, the central bank said. The announcement came after two regulators, the Federal Deposit Insurance Corporation and the Office of the Comptroller of the Currency, issued final rules on stress-tests prescribed by the Dodd-Frank Wall Street reforms. \"The Federal Reserve will begin conducting supervisory stress tests under the final rules this fall for the 19 bank holding companies\" that have already been tested, the Fed said. The banks will test their capital ratios against three economic scenarios, including a worst-case scenario, Fed officials said, speaking on condition of anonymity. In the future, the Fed\'s stress-tests will be conducted on non-banking financial institutions that it determines are systemically important to the financial system. The central bank said it was still identifying those companies.