美国折现率用什么指标？
US Treasury yield curve： 10 year vs 2 year， with the difference in yields subtracted to give a “real” rate of interest. The real rate is what matters for economic growth and inflation； it’s what borrowers (and lenders) are really after.
The chart below shows that over the past 5 years or so this rate has been around zero.
Source： FRED， federalreserve.gov/monetarypolicy/frmpolicy.cfm 注：上图是五年平均的利率曲线，可以看到在2020年2月份疫情之前一直处在低位。
When the economy is doing poorly， unemployment is high， price inflation low， and short-term interest rates near zero， central banks will often cut them further into negative territory， as the Fed did in March and April 2020. In fact， as of May 2020， the 2-year T-bill rate was an unprecedented －1.3%.（See Chart 1.） This was done to stimulate spending on both goods and services—which would help the economy as a whole —as well as to push down long-run nominal bond yields， which should lower borrowing costs across the board.
If you think about it， the reason this policy worked at all was because inflation was so low．In theory， if prices were rising faster than －1.3%， then even if unemployment rates were high， these would not be good times to purchase durable goods like automobiles， homes， and appliances. Consumers would be better off waiting out the current slump until after prices started moving up. The prospect of higher future prices would encourage consumers to spend now， which could kick start the entire economy out of its rut.
Unfortunately， when the economy eventually recovers from COVID-19， this strategy may not work so well. With inflation having already risen substantially since last spring， the risk of higher prices becoming “sticky” means that any additional fiscal spending might lead to even higher inflation， which would undercut the case for lower interest rates. Furthermore， the pandemic has caused major disturbances in global supply chains， and there is no guarantee that these can be fixed anytime soon. If manufacturers have trouble getting the parts they need， this too will boost consumer prices， making the Fed’s job more difficult going forward.