This looks very good although the classic Permanent Portfolio uses long term treasuries (20+ year) rather than medium term (7-10 year). Substituting TLT for IEF gives slightly better results.

So without further ado herewith a very crude version of Harry Browne's
Permanent Portfolio. You will curse it when stocks are booming and you
will bless it during a stock market crash.

So true!

Since 1870 the CAGR on US 10 year T-Bonds has been 4.71%. I dont' have the figures for the 20 year long bond to hand.
US short term 3 month Treasuries achieved a CAGR of 3.97% (from the treasury yield culled from NBER and the Federal Reserve).
Given such similarity across the yield curve over time I'm not sure I' bother with longer dated bonds.

The volatility is huge on the long bond and yields have only one way to go.

Using 10-year Treasuries may be a better choice going forward; I don't know. But my point is that would be a variation on the Permanent Portfolio. Harry Browne's version uses Long Term Treasuries.

Hmm...a dull but worthy performance. A bit of a recent drop but presumably this algo will continue to strut its stuff. You avoid both upside and downside from the S&P 500 for a more comfortable ride through crashes. Interesting to see what happens to bond yields given the unprecedented amount of government borrowing which will now be necessary. But as I have often pointed out bonds do just fine so long as rates rises are not too sharp and swift (see the Volker era in the early 1980s) since higher yields eventually make up for falling prices. Well over 90% of bond returns are from coupon not price change over the long term. Not surprisingly.