[mvilim]

I looked up VFITX. It looks like they pay distributions (i.e. dividends) that are roughly proportional to the expectation of the interest rate over the average maturity of their holdings, so you need to take this into account when considering "what-if". They have paid approximately 1.4% in dividends during 2018. That makes their total losses around 0.6%.

This doesn't fully explain the underperformance of VFITX compared to a 3 year bond (which should have made 8 mo/12 mo * 2% = 1.3% in interest and lost around 0.7% on rising interest rates), a net gain of 0.6%.

So VFITX underperformed a three year bond by 1.2%. 0.13% of this is their management fee (0.2% * 8 mo/12 mo). I'm not able to explain the last 1% of difference.

However, in theory, a bond fund loses just as much value on an interest rate rise as the bonds it is holding lose. In my example above, the bond is worth ~$99 after the increase to a 3% rate, just like the fund. The only difference between the bond and the fund is the choice of when to liquidate or roll.

It's possible that VFITX got unlucky on the timing of their bond rolling (see cousin comment).

[DavidHull]

According to the VFITX portfolio page (https://investor.vanguard.com/mutual-funds/profile/portfolio...), the average maturity of its holdings in 6 years, which probably explains why its performance is different than that of a 3 year treasury bond.

[mvilim]

Five and ten year US bonds have had lost less value than the three year bond in the past 8 months, so that doesn't seem sufficient to explain it (i.e. it makes the difference worse).

That said, I was very loose in my calculations. Without exact knowledge of their holdings and careful calculations, I'm not surprised that the numbers don't fully add up.

[twblalock]

Fair enough, but if someone is interested in holding bonds to maturity it seems like investing in a fund is not actually the same as doing that.