Barclays Capital is set to buy back some $12 billion of collateralized loan obligations and U.S. residential, mortgage-backed securities as new capital rules have made it more costly to keep them off its balance sheet. The U.K. bank said it will take over Protium, the toxic-asset fund it created two years ago, because the prices of underlying assets are improving. Barclay says it will be less costly for it to sell down those assets over the next three years and shorten a loan used by Protium to buy the assets.