Anna Raytcheva’s mortgage-bond bets for Citigroup Inc. lost billions of dollars as the financial crisis raged, but amid new rules meant to curb banks’ risky trading, she’s gambling again, Bloomberg News reported today. Raytcheva’s group in New York manages more than $1 billion for the bank and doesn’t have clients. She has a rare mandate after banks cut or reassigned scores of proprietary traders, driving many to join hedge funds ahead of regulations that will limit the once-lucrative business of speculating for the accounts of the nation’s biggest lenders. The rules, designed to prevent future calamities, haven’t stopped her team: It’s designed to fit within exemptions to foster markets for government securities. Citigroup may be interpreting the exemptions more liberally than other firms, even after past missteps, according to Clifford Rossi, a former risk manager at the bank. The third-largest U.S. lender’s catastrophic losses during the credit crisis prompted a $45 billion taxpayer bailout. Now led by Chief Executive Officer Michael Corbat, 54, it failed a Federal Reserve stress test in March for the second time in three years.