Some big U.S. banks are buying more U.S. government securities as yields start to rise and the Federal Reserve appears ready to taper its bond-buying program—a balance sheet shift that analysts say could boost bank earnings by several percentage points depending on how they play their hands. Bank of America Corp. and Citigroup Inc. on Thursday said they had picked up extra net interest revenue during the quarter by buying securities with higher yields. JPMorgan Chase & Co, however, said on Wednesday that it continues to hoard cash, expecting rates to move higher as Chief Executive Jamie Dimon predicts. Citigroup Chief Financial Officer Mark Mason said the bank has been buying Treasuries and mortgage-backed securities. “We’ve got a strong liquidity position and we’ve been putting some of that to work,” Mason told reporters. Bank deposits have piled higher than ever, fueled by money from Federal Reserve purchases of bonds, government …