By David Carnevali NEW YORK, March 16 (Reuters) - A strong rebound by financials helped Wall Street's main indexes close firmly positive on Thursday, after media reports said some of the country's largest lenders were in talks to aid First Republic Bank. Concerns about banks have rattled the stock market in recent days after the collapse of SVB Financial fueled contagion fears. Weak retail sales figures, as well as data showing a downward trend in producer inflation, on Wednesday had bolstered bets of a small rate hike by the Federal Reserve at its meet concluding on March 22.