When discussing portfolio construction, “Cash” is very different than paper money stuffed under the mattress. The asset code is BIL because cash tracks very short duration government treasury bills. Thanks to the direct backing of the government they are considered the single safest way to hold cash, and historically speaking the return on cash is a lot more dynamic than you may think. In fact, counter to “common knowledge” that is actually quite wrong, properly invested cash is an extremely effective inflation hedge.
The data here tracks government treasury bonds with the lowest default risk and uses the annualized 3-month Tbill rate of the country in question.
Tbills are a little different than most bonds in that they don’t have a coupon payment. They simply sell at a discount to their ultimate redemption price.
While popular historically, in today’s very low interest rate environment a common substitute with slightly higher interest rates and only a little more risk is short term bonds.