Well, funds are just made up of a bunch of bonds that they own. They will list a bond duration, and that's about all you need to know about the future behavior of the bonds, and unfortunately it's also the only thing they publish that's useful. You should expect the fund to perform in the future the way the bonds would. There's nothing reported by a bond fun that you would look at to find that "4%". They simply don't report data about funds that way. They probably should. It should be that every bond in that portfolio does appear to yield 4% to maturity, but the simply don't have a place on that page where they report that.
A second problem with funds is that they may have a goal to keep the duration at some point like for example 5 years. That means they will be selling their bonds with 4 years to go and they'll be shopping for funds with 6 years to go all the time, with NO REGARD to what that does to the performance of the fund or whether it's a good idea. Holding bonds to maturity can be quite different and in fact allows you to say, for sure, that "this bond yields 4% to maturity"; tactical bond investing also can be quite different. I can't name a fund that does it.
This is one of the larger ultra short bond etfs: BIL
1-3 month treasuries. Seems the last month's dividend was ~2.6%
The underlying holdings are now yielding 3.5%+. Subtract the expenses and I don't know what accounts for the difference. I guess it takes a few months for the holdings to catch up to the rising rates, if they're rolling them over?
Yeah, I know it's completely different for longer bonds that people are trading. But it seems for a short-duration product like this they would just be buying and holding for the duration of the bond, then rolling to new issues. (I'm not sure how they actually run this fund).So it's hard to be really clear about this. Bonds are just a simple mathematical products. These bonds are tradeable, and they are saying their bonds are "worth" what they're trading for. So the amount of money you earn is the interest it pays PLUS the amount the face value goes up.
The people doing the trading are smart, so if they can buy brand new bonds paying 4% they just trade old bonds that pay 1% with a 3% per year discount (for instance). That is why the fund's interest yield DOES NOT TELL YOU what you want to know. The total amount of money you make is that plus the fact that the bonds are today trading at a discount, but when they mature, the gov't or other lender has to pay you the full face value.
So, the good news is, if you buy individual bonds, they do try to make sense out of it for you. But funds don't, and the reason really is that it's just not their tradition. The brokerage softwares we use display bond funds and equity funds the same. They've never been forced to calculate and display that.