Sounds super interesting but could you give a layman's explanation please?
You buy a $1000 bond that pays 2 percent for 5 years. Great, that's what you get. A fund buys the same bond and then interest rates rise, so they sell the bond at a slight loss (vs $1000) so they can invest in something with a better return. It becomes a bit of a game and can lose or gain vs the fixed return of buying and holding actual bonds.
Specifically: “Thus, the distinction between a non-rolling ladder (designed to meet date-certain future liabilities) and a rolling ladder (which essentially represents a personal bond fund) is much more important than the difference between a rolling ladder and a bond fund.”
A one-off individual bond purchase, held to maturity, would be the simplest example of a “non-rolling ladder”.
But even then, the individual bond if marked-to-market (or if you needed to liquidate it before maturity date) would have fluctuating market price. It’s only the intent to hold it to maturity that gives one the ability to choose to ignore the intermediate market price. And if you’re reinvesting it into more bonds (a “rolling ladder”) then you do have to care about market prices at reinvestment time regardless.