I might start buying if the yield on the 30 year goes above 6%.
I'd be interested if the ten year treasury yield minus trailing ten year inflation was greater than the inverse CAPE10 ratio!
(who can tell whether or not I'm serious?)
@Radagast, I can't tell! But it sounds like a logical position. You're sort of saying if you could lock in bonds with a real return greater than stock earnings, you'd take it?
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On the OP's question:
I'm assuming that when OP said "the 30 year note", he/she referred to the sale of 30 year bonds by the US Treasury. The last time new US Treasury 30 year bonds were over 10% for very long appears to be 1979-1985.
http://www.macrotrends.net/2521/30-year-treasury-bond-rate-yield-chartBy eye, yields on the 30 year note during that time averaged in the neighborhood of 12%.
But if memory serves, inflation was very scary at that time. I was a kid then; that's what the TV news seemed to be saying. So bonds were probably scary. Looking back, prospective bondholders at the time probably had to worry about the risk of a hyperinflation destroying the value of the bonds, reducing the purchasing power of the bond's payments almost to zero. US had just experienced the highest inflation in its history (1970s). Inflation 1979-1985 was lower but still averaged about 6.8%, with lots of volatility:
http://www.in2013dollars.com/1979-dollars-in-1985So bonds were offering a real (meaning, inflation-adjusted) return of maybe 5% pretax, with significant risk due to uncertainty about inflation. But at the time, the S&P 500 had dividend yields close to 5%, without counting any capital appreciation:
http://www.multpl.com/s-p-500-dividend-yield/tableUnderlying earnings for stocks on the S&P back then were between 9% and 13% of purchase price (P/E ratios from 7.x to 11). So there were reasons to buy stocks instead of bonds at the time, even though stocks had just finished a decade (1970s) of terrible returns.
http://www.multpl.com/tableWe have a long way to go before we would reach 10% returns on a new 30 year Treasury note. If we ever get there again, I suspect things will feel differently than they do today.