A top US bank regulator told lawmakers Wednesday that \"inadequate\" risk controls at JPMorgan Chase led to a $2 billion derivatives loss, as a top senator called for increased scrutiny of Wall Street. Congress is holding a series of hearings on the disastrous derivative trading strategy reported by the bank last month that sent shudders through the still-frail financial system. Thomas Curry, who heads the Office of the Comptroller of the Currency (OCC), was in the spotlight for his organization\'s oversight of the bank unit responsible for the loss. \"The issue at JPMorgan Chase is one of inadequate risk management\" within the chief investment office, Curry said when questioned by the Senate Banking Committee. He said his agency is poring over audit reports and interviewing officials both at JPMorgan and the OCC to establish \"a detailed chronology of events\" leading up to the disastrous loss. \"Our analysis will focus on where breakdowns or failures occurred,\" he said in his testimony. Curry told the packed hearing that while the massive loss affects the bank\'s earnings, it \"does not present a solvency issue.\" JPMorgan Chase has some $1.8 trillion in assets, including $101 billion in Tier 1 common capital, he said. But amid worries that so-called \"too big to fail\" banks like JPMorgan were taking excessive risks that could damage the entire financial system, senators expressed concern that regulators were too lax in monitoring huge trades. \"What did the comptrollers office know, and were you on top of things?\" asked Richard Shelby, the committee\'s ranking Republican. Curry responded that his concern about the bank intensified in April \"as losses increased within the portfolio.\" The OCC focused on \"managing and monitoring the bank\'s efforts to mitigate or de-risk that particular portfolio with the objective of ensuring there is a soft landing of that particular position,\" he said. The series of hearings -- JPMorgan\'s chief executive Jamie Dimon has been invited to testify before Congress twice later this month -- comes amid fierce debate over the Volcker Rule, a potential new policy which would bar banks from trading with their own funds in a bid to prevent them from taking dangerous risks while enjoying government guarantees. Banking Committee chairman Tim Johnson said he disagreed with complaints that new Wall Street reforms urge regulators \"to micromanage\" banks. \"To restore confidence in our financial system after the crisis, we need more, not less, scrutiny of Wall Street\'s activities,\" Johnson said. Senator Patrick Toomey and other Republicans argued that the Volcker rule would merely limit banks\' abilities to manage risk, and would impede their free-market trading. \"I\'m very, very concerned that we have created a monster,\" Toomey told the regulators. There were \"over 100 examiners on the ground full time at JPMorgan alone,\" he noted, and they still failed to spot and interdict the bank\'s alarming losses. He said capital was the essential tool to reduce systemic risk and provide a buffer against banks that get in trouble.