????一些投資者正在購買日本政府債券作為股市低迷之下更為安全的選擇，而另外一些投資者則在購買日本政府債券信用違約掉期，因為他們認為，用不了多久日本政府就會拖欠債務。這兩種投資者之間正進行著一場拉鋸戰。五年期日本政府債券的信用違約掉期價格正在飆升至歷史新高。

????日本國債受到關注的原因很簡單。由于向本國銀行、保險公司和國民出售國債，日本目前已經債臺高筑（預計今年將高達 GDP 的 228%）。其債權人一直允許利率保持在能夠承受的范圍之內，近乎于零。但債務負擔如此之重，即便是利率的微幅增長也會將不可持續的國家收入消耗殆盡。

????當然，這里要說明一點，這種情況是不可持續的。根據國際評級機構標準普爾（Standard & Poor's）的一份報告，日本的人口老齡化將會促使承擔大部分政府債務的機構——日本國內壽險公司和政府養老投資基金——成為凈賣家，以承擔與養老金有關的費用。

????總有一天，日本人口結構的變化會迫使其向國外買家借款，而這些國外買家很有可能會收取日本無力支付的高利率。如此一來，日本就會陷入債務危機。

????然而，這次地震也可能不會導致債券收益飆升，原因有二。

????首先，根據報道，這次地震未必會使保險公司賠付巨大的地震損失，因為僅有 18.5% 的日本家庭擁有地震保險。如果那些承保人不必進行巨額理賠，他們就大可不必清算國債之類的資產。

????事實上，日本債券依然穩定，災后日元甚至更為堅挺。經濟學家把這種現象歸因為以下猜測：日本機構可能會出售美國國庫券來募集資金，而且日本本土公司可能會將資金匯返該國以支付地震損失。日本是除中國之外美國債務的最大買家，當其弄清楚救援和災后清理到底需要多少資金時，也可能會立即停止購買美國國庫券。

????其次，根據日本銀行的數據，日本持有本國債務的 95% 以上。所以即使國外投資者開始減持債券，這些債券也只是整個債券市場的一小部分。

????因此，雖然債務危機的恐慌和以前一樣籠罩著日本，但這在震后短時間內恐難發生。日本政府債券的利率需由國外市場決定之時，才是日本債務問題“清算”之日。

????日本具有向本國機構和國民借款的能力，這在很大程度上加劇了日本對信用的依賴。而現在，在日本最需要保護的時候，同樣的狀況也許會保護其免受嚴酷的市場沖擊。

????There's a tug of war happening right now between investors who are buying Japanese government bonds (JGBs) as a safer alternative to the sinking stock market, and investors who are buying credit default swaps on JGBs because they believe the country is will soon default on its debt. The price of credit defaults swaps on 5-year JGBs is hitting record highs.

????Here's a quick look at why people are scrutinizing Japanese sovereign debt. Japan has been able to rack up a massive debt load (expected to hit 228% of GDP this year) by selling JGBs to its own banks, insurance companies, and citizens. These lenders have allowed interest rates to stay at a very affordable near-zero percent. But with a debt so large, even a small increase in interest rates would start to eat up an unsustainable amount of the country's revenues.

????Certainly there's an argument to be made that this situation is unsustainable. According to a report from Standard & Poor's, Japan's aging population will push the institutions that hold the most government debt -- domestic life insurance companies and the Government Pension Investment Fund -- to become net sellers to support pension-related costs.

????The demographic shift will someday force the country to borrow from foreign buyers, who will likely charge higher interest rates that Japan can't afford to pay. And then you have your debt crisis.

????But there are two reasons that the earthquake may not trigger a sharp rise in yields.

????First, the quake is unlikely to force insurance companies to make massive payments for earthquake damage, since only about 18.5% of Japanese households have earthquake insurance, according to reports. If those insurers don't have to make massive payments, they probably won't have to liquidate assets like JGBs.

????In fact, Japanese bonds have remained stable and the yen has even strengthened since the disaster. Economists have attributed this phenomenon to speculation that Japanese institutions could sell US Treasuries to raise money, and that domestic companies might repatriate money to pay for earthquake damages. Japan, the largest buyer of US debt after China, could also momentarily stop buying Treasuries while it figures out how much it needs to spend on rescue and clean up efforts.

????Second, Japan holds more than 95% of its own debt, according to Bank of Japan data. Even if foreign investors began to unload their bonds, they account for a small part of the overall market.

????So while the specter of a debt crisis hangs over Japan as much as it ever has, it's unlikely to occur in the immediate wake of the earthquake. The day of reckoning for Japan's debt problem will come when foreign markets determine the interest rates on JGBs.

????Japan's addiction to credit was fueled in large part by its ability to borrow from its own institutions and people. Now that same dynamic may shield the country from the harsh forces of the market at a time when it needs the protection the most.