????歐洲主權債務危機正在慢慢地將全球經濟推回谷底。解決這場危機為什么這么苦難？答案再次歸結為銀行業過度承擔的風險和它們所采取的杠杠率。10月末歐洲領導人終于說服銀行業將手中的希臘債務減免50%，雖然希臘近期倡議的全民公決可能阻礙這一方案的實施。但債務重組也就只能進行到這個程度，因為歐洲銀行業沒有足夠的資本金來消化未來的損失，國際貨幣基金組織（IMF）估計損失將達到2,800億美元或更高。那么，為什么歐洲銀行業的資本金會如此單薄？責任完全在歐洲銀行業和它們的監管機構身上。

????銀行業監管機構評估一家銀行的資本金是否足以應對其貸款、投資和其他資產的損失時會考慮這些資產的風險水平。比方說，美國國債的風險低于無擔保信用卡貸款額度（我們希望如此）。但實際操作有很大的靈活性，而且歐洲監管機構在這方面給予銀行的空間也遠大于美國。因此，從上世紀90年代中期開始，歐洲銀行業就一直在下調潛在資產損失的估算值，如今依然聲稱它們的資產安全性是美國銀行的兩倍。

????歐洲采用復雜的巴塞爾協議II（Basel II），進一步激化了這個問題——巴塞爾協議II事實上是讓銀行高管自己來確定資產的風險水平。簡直是幼稚。聲稱資產風險低符合銀行高管的利益，因為這樣銀行就能實現杠桿率和凈資產回報率最大化，進而提高高管的報酬和分紅。事實上，即使是在大蕭條時期，債務拖欠和違約增加，大多數歐洲銀行仍然聲稱它們資產的安全正在提高。

????有美國聯邦存款保險公司（FDIC）擔保的美國銀行業在如何確定資產風險水平方面受到更為嚴格的監管規范，同時資本金充足的銀行須持有至少相當于資產總額5%的資本金，無論它們自認資產風險水平如何。因此，對于任何資產，無論是現金、美國國債、還是據稱安全的按揭貸款，銀行都必須至少持有相當于資產額5%的資本金。歐洲銀行業沒有此類“杠杠率”，而且巴塞爾協議II也允許它們將主權債券視為零風險資產。這就是它們累積了近3萬億美元主權債券的原因之一。

????去年，巴塞爾銀行監管委員會（Basel Committee on Banking Supervision）終于批準了的3%國際杠桿率，盡管這一比例仍然過低。即便是這么低的要求，該委員會的研究發現全球仍有超過 40%的大銀行都需要補充資本金。與此同時，歐洲銀行管理局（European Banking Authority）正在將歐洲銀行業的普通股權益資本比率提高到9%，大大高于巴塞爾協議II的2%標準，基本相當于新的巴塞爾協議III的標準。但即便是采用9%的標準，眾多歐洲銀行仍將保持極端的杠桿率，因為它們對風險所持的觀點仍然相當樂觀。

????作為補充，歐洲監管機構應該采用巴塞爾協議III的3%杠桿率，考慮到會計標準的不同所需要做出的調整，更好的選擇是采用美國的5%標準。此外，歐洲銀行管理局還應該采用更現實的損失估算值，以更接近國際貨幣基金組織和私營部門分析人士給出的數值。如果銀行不得不接受股本被攤薄或暫時被國有化，那就接受現實吧。

????巴塞爾委員會需要行動迅速一點，采用由監管機構（而非銀行）設立的風險衡量標準，貫徹于所有銀行。美國監管機構犯過很多錯，但由于我們保持了杠桿率要求并暫緩執行巴塞爾協議II ，由聯邦存款保險公司擔保的銀行財務狀況一直比其他金融機構更為穩健。銀行的資本金標準不應由銀行說了算。公眾需要看到更完善的監管。銀行監管機構應當恪盡職守，設立最低資本金要求就是它們的職責所在，而不是存在利害關系的銀行高管們的職責。

????The European sovereign debt crisis is slowly driving the global economy back into the ditch. Why is this crisis so unresolvable? The answer comes back once again to excess risk taking and leverage in the banking sector. In late October, Europe's leaders finally persuaded the banks to take a 50% cut on the Greek debt they hold, although this agreement could be jeopardized by Greece's recent call for a referendum on its bailout package. But debt restructuring will get you only so far because Europe's banks do not have sufficient capital to absorb future losses, which the IMF estimates will be $280 billion or higher. And why are Europe's banks so thinly capitalized? That responsibility rests squarely with European banks and their regulators.

????When bank regulators assess the adequacy of a bank's capital to handle losses from its loans, investments, and other assets, they take into account the riskiness of those assets. For instance, an investment in U.S. Treasuries carries lower risk (we hope) than an unsecured credit card line. The process, however, is more art than science, and in Europe regulators have given their banks much more leeway in making those determinations than banks have in the U.S. As a result, since the mid-1990s European banks have continually lowered their estimates of likely losses on their assets and now say their assets are twice as safe as those held by U.S. banks.

????The problem has been exacerbated by Europe's adoption of a complex Basel II methodology, which essentially lets bank managers use their own judgment in determining the riskiness of their assets. That is naive. It is in a bank manager's interest to say his assets have low risk, because it enables the bank to maximize leverage and return on equity, which in turn can lead to bigger pay and bonuses. Indeed, even during the Great Recession, as delinquencies and defaults increased, most European banks were saying their assets were becoming safer.

????The U.S., which has tighter rules governing how FDIC-insured banks determine the riskiness of assets, requires well-capitalized banks to hold capital equal to at least 5% of total assets, regardless of how risky they think the assets are. So for any asset, be it cash, U.S. Treasury securities, or supposedly safe mortgages, banks must hold at least 5% capital against it. European banks do not have this kind of "leverage ratio," and Basel II has allowed them to treat sovereign debt as having zero risk. That is one of the main reasons they have loaded up on nearly $3 trillion of it.

????Last year the Basel Committee on Banking Supervision finally approved a still-too-low 3% international leverage ratio. Even at that permissive level, the committee's own research suggests that more than 40% of the world's largest banks would have to raise capital. At the same time, the European Banking Authority (EBA) is raising European banks' common equity capital requirement to 9%, a huge jump from the Basel II standard of 2% and roughly equivalent to the new Basel III standards. But even at 9%, a large number of European banks will continue to operate at extreme levels of leverage because of their rosy views of risk.

????European regulators should supplement this requirement with the Basel III 3% leverage ratio -- or even better, the U.S. 5% requirement, adjusting for accounting differences. The EBA should also use realistic loss estimates more in line with those of the IMF and private analysts. If banks have to accept dilution of their stock or temporary nationalization, so be it.

????The Basel committee needs to move swiftly to adopt standardized measures of risk set by regulators, not banks, and to consistently apply them across all institutions. U.S. regulators made many mistakes, but because we maintained our leverage ratio and delayed Basel II implementation, FDIC-insured banks have remained much more stable than other financial institutions. Bank capital standards should not be an insider's game. The public deserves better. Bank regulators should do their job, and it is their job, not the job of conflicted bank managers, to set minimum capital levels.