美联储考虑曲线退出经济刺激行动

    或许本•伯南克只能选择让影子银行体系膨胀，才能终止对债券市场的操纵。至少，有些人是这么认为的。

    几个月来，美联储（Federal Reserve）内外均有传言称，这家美国央行可能只能采用非常规方式来退出债券购买计划。现在可能有更准确的说法了。周一，在伯南克宣布将延后退出刺激计划（即所谓的“逐步缩减”）四天后，纽约联邦储备银行行长威廉•杜德利表示，美联储正在测试通过所谓的“逆回购”方式来实现利率逐步上调。

    美联储在逆回购过程中是从经济体系中抽取资金：银行、货币市场基金和其他参与者为美联储提供隔夜资金，获得收益。它有点像贷款，但不完全是。美联储把美国国债作为担保品给银行。回购利率事实上能确定短期利率，因为没人会愿意按低于美联储所愿意支付的无风险利率来提供贷款。

    这不是美联储通常上调利率的方式。过去它总是通过出售国债来推高利率。但在美联储持有的美国国债和抵押债超过3.5万亿美元后，这招已经不管用了。需要比通常出售更多的债券才能影响市场。而且，为了安抚市场对于美联储债券购买计划的担忧，伯南克基本上已承诺美联储实际上绝不会出售这些债券。

    杜德利强调称，这只是一项测试。但美联储的债券购买计划实施时间越长，就越可能最终只能实施逆回购或类似的方式。

    美联储提出逆回购计划同时，美联储很多理事都在讨论是否需要遏制回购市场和影子银行体系的其他领域。回购通常被视为影子银行体系的一部分，因为这些贷款的期限太短，一般不会计入银行体系的总体杠杆指标。而且，很多回购是由货币市场基金进行的，它们从技术上讲并不是银行。就在上周，美联储理事丹尼尔•塔鲁洛表示，监管机构应当把重点放在打击短期融资市场上。

    银行咨询人士伯特•伊利说：“具有讽刺意味的是，在他们考虑采取逆回购方式的同时，很多美联储人士表示了对回购市场的担忧。”

    但塔鲁洛主要担心的是银行使用回购市场获得短期资金，然后用于长期高风险资产。很多人相信，使用短期融资导致金融危机进一步恶化。

    起初，美联储的计划不会造成这种情况。银行和货币市场基金将给美联储提供贷款。但美联储的计划是从回购市场抽回大量资金。而这些资金不太可能在美联储计划结束后离场，至少不会立即离场。接下来可能利用这些短期资金的就是银行。

    Ben Bernanke may have to pump up the shadow banking system in order to stop manipulating the bond market. At least that's how some see it.

    For months, there has been talk inside and outside the Federal Reserve that the U.S. central bank might have to use an unorthodox method to exit its bond buying program. That could be even more accurate now. On Monday, four days after Bernanke announced the Fed would put off winding down the program -- the so-called taper -- New York Fed president William Dudley said the U.S. central bank was testing so-called reverse repos as one method to eventually increase interest rates.

    In reverse repos, the Fed drains money from the economy by having banks, money market funds, and others give it money overnight for a fee. It's kind of like a loan, but not quite. The Fed gives banks Treasury bonds as collateral. The rate on the repo effectively sets short-term interest rates, because why would anyone make a loan for less when the Fed is willing to pay risk-free?

    That's not how the Fed typically raises interest rates. Historically, it has sold Treasury bonds to drive up rates. But that may no longer work because the U.S. central bank now has over $3.5 trillion in Treasury and mortgage bonds. It would take much more selling than usual to move the market. What's more, to calm market fears about its bond buying program, Bernanke essentially pledged that the U.S. central bank would never actually sell the bonds.

    Dudley stressed it was just a test. But the longer the Fed's bond buying goes on, the more likely the Fed will eventually have to deploy reverse repos or something like it.

    The reverse repo plan comes at a time when a number of Fed governors have talked about the need to rein in the repo market and other areas of the shadow banking system. Repos are generally considered part of the shadow banking system because the loans are so short that they generally don't get recorded in overall leverage measures of the banking system. What's more, a lot of repos are made by money market funds, which are technically not banks. Just last week, Fed governor Daniel Tarullo said regulators should focus on cracking down on short-term funding markets.

    "It's ironic that they would do this at a time when a number of people in the Fed had said they are worried about repos," says Burt Ely, a bank consultant.

    Tarullo, however, is chiefly worried about banks using the repo market to get short-term loans to fund longer-term riskier assets. Many believe the use of short-term funding made the financial crisis worse.

    Initially, the Fed's plan wouldn't do that. Banks, along with money market funds, would be making loans to the Fed. But the Fed's program is bound to draw a lot of money to the repo market. And that money is unlikely to leave after the Fed program is over, at least not immediately. The next likely user of those short-term funds: banks.