BlackRock, Pimco sue over billions in mortgage securities lossesThe lawsuits, filed in New York state court, claim the trustees breached their duties to investors by failing to force lenders and sponsors of the securities to repurchase defective loans, the suits claim. The investors are seeking damages for losses that exceed $250 billion and relate to over 2,200 residential mortgage-backed securities trusts issued between 2004 and 2008, according to a person familiar with the cases.