Trillions: How a Band of Wall Street Renegades Invented the Index Fund and Changed Finance Forever

a) there’s nothing in the boglehead philosophy that defines it as 60/40. You can start reading here https://www.bogleheads.org/wiki/Bogleheads%C2%AE_investment_philosophy b) only a subset of bogleheads attempted to hold uncorrelated assets, partly because correlations routinely change and to find an uncorrelated asset (to equities) that also has a positive expected return is difficult (because everyone wants it). The redeeming quality of short term bonds is low volatility Here’s a graph of stock/bond changing through time https://www.bogleheads.org/forum/viewtopic.php?p=8595846#p8595846 c) MPT is generally considered to have begun with Markowitz in 1952, well before anything about bogleheadism existed. The logic of low-cost index funds flows from MPT and experience. Here are some good book on the history of it all it https://www.amazon.com/Trillions-Renegades-Invented-Changed-Finance/dp/0593087682 https://www.amazon.com/Capital-Ideas-Improbable-Origins-Modern/dp/0471731749 d) commodities, etc., have been discussed extensively and for decades on the forum. A simple search will bring up lots of discussions

here is a good history https://www.amazon.com/Trillions-Renegades-Invented-Changed-Finance/dp/0593087682