QE2, in which the Fed bought long-term government bonds, did not have a discernible effect on long-term government interest rates. Indeed, with its recent decision to pursue QE3, the Fed is focusing once again on the mortgage-backed securities market; but, given that the market is much healthier now, it is unclear how much good this will do.
但是，其他非常规政策的实施是为了刺激经济，而不是对付萎靡的市场。其效果要小得多。美联储购买长期政府债券的QE2就没有对长期政府利率起到可以识别的效果。事实上，在最近决定推出的QE3中，美联储的焦点再次集中在了按揭支持证券市场；但是，如今该市场健康状况已有重大改善，因此QE3能起到多少作用还不好说。