Goldman Sachs faces lawsuits totaling over $15.8 billion worth of mortgage securities, according to the quarterly Form 10-Q filing.  That's more than a 30-fold increase from the amount disclosed just 3 months earlier - which was $485 million.  Goldman management estimates that it's "reasonably possible" that losses on litigation could amount to $2.6 billion. The figures jumped this quarter, in part, because investors in mortgage-backed bond deals have raced to take legal action or enter settlement negotiations before statutes of limitations expire, and as investors continue to worry about banks' exposure to big lawsuits. Goldman said it has entered agreements with some of the potential plaintiffs to stop statutes of limitations from running, thereby allowing negotiations to take place.  Goldman did not provide estimates how much it might expect to pay in these settlements. Source of the Largest Increase? The bank, along with 16 other large Wall Street banks, were sued by the Federal Housing Finance Agency, which accused Goldman of misrepresenting the quality of $11.1 billion worth of residential mortgage-backed securities on sales to Fannie Mae and Freddie Mac. The above numbers do not include early-stage litigation - i.e., cases in which management believes another party may cover losses - or those in which plaintiffs have not sought specific damages.  In many cases, "management is generally unable to estimate a range of reasonably possible loss." Morgan Stanley made similar disclosures in its quarterly report filed on Monday. The explanations come months after the SEC began pressuring big banks to disclose more information about their legal-loss exposures.   [Reuters, 11/9/11]