作者：正月鼠 在 海归商务 发贴, 来自【海归网】 http://www.haiguinet.com
这是美国财政部的声明（节选）：
. Beginning February 18, 2002, Treasury ceased publication of the 30-year constant maturity series. Instead, from February 19, 2002 through May 28, 2004, Treasury published a Long-Term Average Rate, "LT>25," (not to be confused with the Long-Term Composite Rate, definitions below). In addition, Treasury published daily linear extrapolation factors that could be added to the Long-Term Average Rate to allow interested parties to compute an estimated 30-year rate. On June 1, 2004, Treasury discontinued the "LT>25" average due to a dearth of eligible bonds. In place of the "LT>25" average, Treasury published the Treasury 20-year Constant Maturity rate on this page along with an extrapolation factor that was added to the 20-year Constant Maturity to obtain an estimate for a theoretical 30-year rate. On February 9, 2006, Treasury reintroduced the 30-year constant maturity and is no longer publishing the extrapolation factor.
消息来源：https://www.ustreas.gov/offices/domestic-finance/debt-management/interest-rate/ltcompositeindex.shtml
以下内容转贴自wikipedia（节选）:
Treasury bond
Treasury bonds (or T-Bonds) mature in ten years or longer. They have coupon payment every six months like T-Notes, and are commonly issued with maturity dates of ten and thirty years. The secondary market is highly liquid, so the yield on the most recent T-Bond offering was commonly used as a proxy for long-term interest rates in general. This role has largely been taken over by the 10-year note, as the size and frequency of long-term bond issues declined significantly in the 1990s and early 2000s.
The U.S. Federal government stopped issuing the well-known 30-year Treasury bonds (often called long-bonds) on October 31, 2001. As the U.S. government used its budget surpluses to pay down the Federal debt in the late 1990s, the 10-year Treasury note began to replace the 30-year Treasury bond as the general, most-followed metric of the U.S. bond market. However, due to demand from pension funds and large, long-term institutional investors, along with a need to diversify the Treasury's liabilities - and also because the flatter yield curve meant that the opportunity cost of selling long-dated debt had dropped - the 30-year Treasury bond was re-introduced in February 2006. This will bring the U.S. in line with Japan and other European governments issuing longer-dated maturities amid growing global demand from pension funds. Some countries, including France and the United Kingdom have begun offering a 50-year bond, known as a Methuselah.
消息来源：https://en.wikipedia.org/wiki/Treasury_bond#Treasury_bond
看了一些材料，说2001年10月时，美国停止发行30年国库券。是什么原因使美国财政部作出这个决定? 和当年的911有什么联系？从那以后，美国政府有没有大量回购它的国库券呢？
之后直到今年美国才重新发行30年国库券。上面说是应机构投资者和养老基金的要求。究竟是不是这回事？
作者：正月鼠 在 海归商务 发贴, 来自【海归网】 http://www.haiguinet.com
