The biggest U.S. bank by assets has already disclosed $2 billion of paper losses, and Chief Executive Jamie Dimon said it could lose another $1 billion or more. A spokeswoman for the bank declined to comment, although Mr. Dimon has said the total paper trading losses will be volatile depending on day-to-day market fluctuations. In the four trading days since Mr. Dimon’s disclosure, the market has moved at least 15 to 20 basis points more against JPMorgan, he said. Many of the positions are highly illiquid, making them difficult to value for regulators and the bank itself. JPMorgan was such a significant player in the CDX NA IG 9 index that one of its traders, Bruno Iksil, was dubbed the "London whale" in the markets. In its simplest form, traders said, the complex position assembled by the bank included a bullish bet on an index of investment-grade corporate debt, later paired with a bearish bet on high-yield securities, achieved by selling insurance contracts known as credit-default swaps.  Simon Dawson/Bloomberg News 
 
 The trading losses suffered by JPMorgan Chase have surged in recent days, surpassing the bank’s initial $2 billion estimate by at least $1 billion, according to people with knowledge of the losses.
– JPMorgan's $2 billion trading loss has become a $3 billion-and-counting loss with dizzying speed, insiders tell the New York Times. CEO Jamie Dimon predicted that the loss could double within a few quarters, but the extra billion in trading losses has come in just four trading days as hedge funds and other investors smell blood and bet against the positions the bank is believed to have held to hedge against defaults. JPMorgan's "London whale" trader was such a big player on the obscure indexes at the heart of the bank's problems that other traders are finding it easy to identify his trading positions, Reuters notes. "When someone is that big in the market, anonymity really goes out the window," notes a debt trader. The Justice Department and Federal Reserve are probing the losses, which experts say should never have been allowed to happen at a bank with government-backed deposits. But JPMorgan remains relatively healthy, despite the losses. The $3 billion loss would need to double to wipe out its profit from the second quarter of this year.