????多年以來，摩根大通（JPMorgan Chase）這家世界上最冒險的銀行每每總能涉險過關。當然，一路上小麻煩不斷。但基本上，投資者對于這家由杰米?戴蒙領導的銀行總是能放手不管。次貸問題：過去你們已經證明，你們能應付。止贖問題：我們堅信你們已安排了最好的人手。相當于印度GDP的衍生品投資組合：我們相信你們掌握著足夠的資金。

????事實上，盡管摩根大通擁有如此龐大的規模、復雜性和風險，但投資者們允許戴蒙和摩根大通以華爾街最低的資本緩沖（即可抵御損失的權益資本）一路“前行”。如果對摩根大通的貸款和投資按風險進行分類（這種分類雖不可靠但仍被華爾街采用），該行的資本充足率僅為10%。而花旗（Citigroup）、高盛（Goldman Sachs）分別為13%和15%。

????不過，這樣的差距似乎并沒有讓投資者感到不安。摩根大通的股票估值一度居華爾街前列。直到最近，它還是少數幾家市凈率高于1的大銀行之一。這意味著華爾街認為，該公司實際價值超出其賬面價值。花旗目前的市凈率僅為0.5倍。

????然而，上周，這一切全都變了。上周四下午，戴蒙通過一個緊急電話會議告訴分析師們，過去40天摩根大通首席投資辦公室在一場交易中損失了20億美元；該部門原本應通過投資，降低該行風險，而不是加劇風險。上周五，摩根大通股價狂跌近10%，收盤價不到37美元。

????有些人只看這20億美元損失，認為對于通常每季盈利50億美元并擁有550億美元現金的一家銀行來說，算不了什么。毫無疑問，摩根大通能處理好這事。事實上，考慮到該部門所從事的所有其他交易，該部門合計損失降至8億美元。整體而言，該行這個季度看起來仍然有望獲得高額利潤。

????但實際損失將遠遠超出這些。首先，摩根大通在這場交易中的最終損失可能超出已經披露的金額。有報道稱，這項讓摩根大通陷入麻煩的交易規模可能高達1,000億美元，主要由英國一名外號“倫敦鯨”的交易員操盤。摩根大通絕不會損失1,000億美元那么多。但像摩根大通這樣對某一指數進行多倍押注的交易可能需要付出昂貴的代價才能解除，必須與信用度高的大公司進行交易。戴蒙在分析師電話會議上表示，該行在這項交易上的損失可能會進一步擴大，但他沒有透露具體數字。

????For years, JPMorgan Chase (JPM), perhaps the riskiest bank in the world, got a pass. Sure there were minor hiccups along the way. But basically investors had the attitude with the bank run by Jamie Dimon that they were going to be hands off. Sub-prime mortgage loans: You've proved you can handle them. Foreclosure problems: We're sure you've got your best people on it. A derivative portfolio roughly the size of the GDP of India: We trust that you have covered your bets.

????In fact, despite its huge size and complexity and risk, investors have allowed Dimon and JPMorgan to skate by on one of the smallest capital cushions, which is how much equity you have to protect against losses, on Wall Street. When you sort JPMorgan's loans and investments by riskiness, a dubious calculation, but used by Wall Street nonetheless, the bank holds an equivalent of just 10% of that as capital. That compares to 13% at Citigroup (C) and 15% at Goldman Sachs (GS).

????That shortfall, though, didn't seem to bother investors. JPMorgan's shares were rewarded with one of the richest valuations on Wall Street. Until recently, it was one of the few big banks to trade above book value, meaning Wall Street believed it was worth what it said. Citigroup's shares trade at a price-to-book of 0.5.

????This week, all that changed. On Thursday afternoon, Dimon told analysts in an emergency conference call that JPMorgan's chief investment office, a division that is supposed to place investments that lower the risk of the bank, not increase it, had lost $2 billion on a trading strategy in the past 40 days. JPMorgan's shares fell nearly 10% on Friday and closed at just under $37.

????Some have focused just on the $2 billion loss, commenting that it's not that big a deal for a bank that has typically been earning $5 billion every three months and has $55 billion in cash. There's no question JPMorgan can handle it. In fact, factor in all of the division's other trades, and the bank's loss from the division shrinks to $800 million. Overall, the bank will still likely show a hefty profit this quarter.

????But the actual cost of the loss will be much bigger than that. First of all, JPMorgan could end up losing more on the bet than it has already disclosed. Others have reported that the trade that got JPMorgan into trouble, which is mostly attributed to a single trader who is based in the UK and has come to be known as the London Whale, could be as large as $100 billion. The bank won't lose anywhere close to that. But transactions like the one JPMorgan appears to have, where it makes multiple bets involving a particular index, in this case one that has to do with large, credit-worthy companies, can be very costly to unwind. Dimon on the conference call with analysts said the bank's losses on the trade are likely to increase but he didn't say how much.